Exclude every trace of these organisms, and no change occurs.
Some wound in the succulent tissues has become infected by the organisms referred to, and their continued action prevents healing.
Many objects in nature, organisms especially, seem to resemble the works of human design; there fore with high probability we infer a designing mind behind nature, adequate to the production of these special results.
This is especially the case in the lichens (symbiotic organisms composed of a fungal mycelium in association with algal cells), which are usually exposed to very severe fluctuations in external conditions.
Cellulose, the material of which vegetable cell-walls are almost universally composed, at any rate in their early condition, is known to occur, though only seldom, among animal organisms. Such forms as Volvox and the group of the Myxomycetes have been continually referred to both kingdoms, and their true systematic position is still a subject of controversy.
The evidence against this view may be classed under two heads: first, comparative evidence; hydroids very different in their structural characters and widely separate in the systematic classification of these organisms may produce medusae very similar, at least so far as the essential features of medusan organization are concerned; on the other hydroids closely allied, perhaps almost indistinguishable, may produce gonophores in the one case, medusae in the other; for example, Hydractinia (gonophores) and Podocoryne (medusae), Tubularia (gonophores) and Ectopleura (medusae), Coryne (gonophores) and Syncoryne (medusae),-and so on.
Within it or its modifications all the vital phenomena of which living organisms are capable have their origin.
pelagic organisms, floating on the surface of the open sea, propelling themselves feebly by the pumping movements of the umbrella produced by contraction of the sub-umbral musculature, and capturing their prey with their tentacles.
At present, therefore, classifications of the Hydromedusae have a more or less tentative character, and are liable to revision with increased knowledge of the life-histories of these organisms. Many groups bear at present two names, the one representing the group as defined by polyp-characters, the other as defined by medusa-characters.
The study of simple organisms, many of which consist of nothing but a little mass of protoplasm, exhibiting a very rudimentary degree of differentiation, so far as our methods enable us to determine any at all, shows that the duties of existence can be discharged in the absence of any cell-wall.
Differences connected with the mode of supply of nutritive material do exist, but they are mainly correlated with the structure of the organisms, which makes the method of absorption different.
Those organisms which possess the latter are a little higher in the scale of life than those which remain unclothed by it, but a comparison of the behaviour of the two quickly enables us to say that the membrane is of but secondary importance, and that for those which possess it, it is nothing more than a protective covering for the living substance.
The resin contains, in addition to the beautifully preserved plant-structures, numerous remains of insects, spiders, annelids, crustaceans and other small organisms which became enveloped while the exudation was fluid.
Di,fferentiation.Any account of the general morphology of living organisms is incomplete if it does not include some attempt at an explanation of its causation; though such an attempt cannot be carried far at the present time.
In other words, are these organisms not spontaneously generated?
In 1857 Pasteur decisively proved that fermentation was a physiological process, for he showed that the yeast which produced fermentation was no dead mass, as assumed by Liebig, but consisted of living organisms capable of growth and multiplication.
There are two distinct types of fermentation: (1) those brought about by living organisms (organized ferments), and (2) those brought about by non-living or unorganized ferments (enzymes).
They may bear accessory filaments or tentilla (f'), covered thickly with batteries of nematocysts, to which these organisms owe their great powers of -offence and defence.
For he proved that the various changes occurring in the several processes of fermentation - as, for example, in the vinous, where alcohol is the chief product; in the acetous, where vinegar appears; and in the lactic, where milk turns sour - are invariably due to the presence and' growth of minute organisms called ferments.
Brewers' wort remains unchanged for years, milk keeps permanently sweet, and these and other complex liquids remain unaltered when freely exposed to air from which all these minute organisms are removed.
Might one suggest that organisms seem at least to be a working up of inorganic matter for new ends, viz.
This investigator just missed a great discovery, for he did not consider the spherical forms to be living organisms but compared them with starch granules.
If our knowledge of the life-histories of these organisms were perfect, their polymorphism would present no difficulties to classification; but unfortunately this is far from being the case.
Free-swimming organisms without cell-membranes exist in both, and from them series of forms can be traced in both directions.
All organisms, then, are closely adapted to their surroundings.
In the case of land and fresh-water organisms the sea is the chief barrier; in the case of marine organisms, the land.
It is only comparatively recently that the methods of histological investigation used by animal physiologists have been carefully and systematically applied to the study of the vegetable organisms. They have, however, been attended with wonderful results, and have revolutionized the whole study of vegetable structure.
Corals and other quick-growing cal- careous marine organisms are the most powerful in this respect by creating new land in the ocean.
While the tendency is for the living forms to come into harmony with their environment and to approach the state of equilibriumby successive adjustments if the environment should happen to change, it is to be observed that the action of organisms themselves often tends to change their organisms environment.
C. Geographical Distribution The study of the extinct organisms of any country leads to a proper appreciation of its existing flora and fauna; while, on the other hand, a due consideration of the plants and animals which may predominate within its bounds cannot fail to throw more or less light on the changes it has in the course of ages undergone.
Thorpe Cloud, it is highly fossiliferous, but it is usually somewhat barren except for abundant crinoids and smaller organisms. It is polished in large slabs at Ashford, where crinoidal, black and "rosewood" marbles are produced.
It is sometimes forgotten, when discussing questions of animal nutrition, that all the food materials of all living organisms are prepared originally from inorganic substances in exactly the same way, in exactly the same place, and by the same machinery, which is the chlorophyll apparatus of the vegetable kingdom.
The swellings have been found to be due to a curious hypertrophy of the tissue of the part, the cells being filled with an immense number of minute bacterium-like organisms of V, X or Y shape.
This property of living substance can be proved in the case of the cells of the higher plants, but it is especially prominent in many of the more lowly organisms, such as the Bacteria.
We find the ultimate explanation of this in the facts that all organisms vary, and that their variations are inherited and, if useful, perpetuated.
The distribution of living organisms is a complex problem, a function of many factors, several of which are yet but little known.
Different species of organisms come to perfection in different climates; and it may be stated as a general rule that a species, whether of plant or animal, once established at one point, would spread over the whole zone of the climate congenial to it unless some barrier were interposed to its progress.
The labours of Golgi, Marchiafava, Celli and others established the nature of the parasite and its behaviour in the blood; they proved the fact, guessed by Rasori so far back as 1846, that the periodical febrile paroxysm corresponds with the development of the organisms; and they showed that the different forms of malarial fever have their distinct parasites, and consequently fall into distinct groups,.
This semester we will devote our attention to studying the abiological processes of certain non-living organisms.
If these change, as we know they have changed, the organisms must change too, or perish.
The observation of the effects of varying conditions in modifying living organisms.
This has taken the form of inoculating the soil with the particular organism required by the particular kind of leguminous crop. To this end the endeavour has been made to produce preparations which shall contain in portable form the organisms required by the several plants, and though, as yet, it can hardly be claimed that they have been generally successful, the work done justifies hopes that the problem will eventually be solved in a practical direction.
Competition, in the Darwinian sense, is characteristic not only of modern industrial states, but of all living organisms; and in the narrower sense of the " higgling of the market " is found on the Stock Exchange, in the markets of old towns, in medieval fairs and Oriental bazaars.
Among those who have considered that it is derived from the decomposition of both animal and vegetable marine organisms may be mentioned J.
Similarly there is a difference of opinion as to the conditions under which the organisms have been mineralized, some holding that the process has taken place at a high temperature and under great pressure; but the lack of practical evidence in nature in support of these views has led many to conclude that petroleum, like coal, has been formed at moderate temperatures, and under pressures varying with the depth of the containing rocks.
Consideration of the evidence leads us to the conclusion that, at least in commercially valuable deposits, mineral oil has generally been formed by the decomposition of marine organisms, in some cases animal, in others vegetable, in others both, under practically normal conditions of temperature and pressure.
Organic Chemistry While inorganic chemistry was primarily developed through the study of minerals - a connexion still shown by the French appellation chimie minerale - organic chemistry owes its origin to the investigation of substances occurring in the vegetable and animal organisms. The quest of the alchemists for the philosopher's stone, and the almost general adherence of the iatrochemists to the study of the medicinal characters and preparation of metallic compounds, stultified in some measure the investigation of vegetable and animal products.
If the plants are subjected to some process, before mounting, by which injurious organisms are destroyed, such as exposure in a closed chamber to vapour of carbon bisulphide for some hours, the presence of pieces of camphor or naphthalene in the cabinet will be found a sufficient preservative.
This marks them off from such reflex acts as are unconsciously performed, and from the tropisms of plants and other lowly organisms. There remains, however, the difficulty of finding any satisfactory criterion of the presence of consciousness.
We have reason to believe that some organisms profit by experience and show that they do so by the modification of their behaviour in accordance with circumstances.
Only the careful observation of organisms throughout the earlier phases of their life-history can the closely related factors be distinguished with any approach to scientific accuracy.
It should be remembered that such comparatively simple activities, though there is little about them to arrest popular attention, are just the raw material out of which the normal active life of such organisms is elaborated, and that for scientific treatment they are therefore not less important than those more conspicuous performances which seem at first sight to call for special treatment, or even to demand a supplementary explanation.
The portion of Nassau harbour known as the Sea Gardens exhibits an extraordinarily beautiful development of marine organisms.
It became clear that only very rough estimates of the numbers of planktonic organisms in a volume of sea-water as large as (say) 10 cubic metres could be made, but that these estimates could nevertheless be trusted to show very marked regional and seasonal differences.
Therefore all life in the sea (as on land) depends on the power which the holophytic organisms possess of synthesizing mineral substances into organized tissues.
Clearly, however, the vast quantity of living substance in the ocean is built up from materials that are present in the sea-water as an exceedingly dilute solution, and the solution is dilute just because organisms are incessantly utilizing it.
or March) and the days begin to lengthen the phyto-planktonic organisms begin to reproduce.
Therefore the animal organisms, as a rule, reproduce in the spring or early summer just after the vernal phyto-plankton maximum.
The dead bodies of organisms fall down from the surface and are slowly resolved into products of putrefaction, which gradually pass into the mineral forms, nitrates, carbonic acid and ash.
Nitrogen is always being synthesized from the atmosphere (by plants, and by electrical discharges which combine nitrogen and oxygen), and this combined nitrogen is either utilized by land organisms or is washed down into the sea in the water of the rivers.
The silica, in the form of diatom or radiolarian skeletons, is eventually deposited on the ocean floor after the death of the organisms. Most of the fine colloidal clay is, however, deposited as river-sludges when the fresh water carrying it mixes with denser sea-water.
It is not at all certain that the masses on which coral reefs are built consist entirely of the remains of the skeletons of reef-forming organisms and it is probable that chemically precipitated carbonate of lime predominates.
The water which bears the oxygen for respiration and the minute organisms upon which the Brachiopod feeds is swept into the mantle cavity by the action of the cilia which cover the arms, and the eggs and excreta pass out into the same cavity.
CHAETOSOMATIDA, a small group of minute, free-living, aquatic organisms which are usually placed as an annex to the Nematoda.
(After Lankester, loc. cit.) has as many structure of the prosoma, and must play an important part economy of these organisms. In Limulus (figs.
Secondly, identity of structure in two organisms does not necessarily indicate that the identical structure has been inherited from an ancestor common to the two organisms compared (homogeny), but may be due to independent development of a like structure in two different lines of descent (homoplasy).
A species of Acarus is recorded as infesting a store of powdered strychnine and feeding on that drug, so poisonous to larger organisms. Reference to literature (40).
Meanwhile the union of so many distinct political organisms had reduced the party system to chaos, and the first two years were taken up by a process of regrouping, the dominant issue being Centralism versus Federalism.
Darwin's introduction of thremmatology into the domain of scientific biology was accompanied by a new and special development of a branch of study which had previously been known as teleology, the study of the adaptation of organic structures to the service of the organisms in which they occur.
All organisms are essentially and necessarily built up by such correlated variations.
Another special distinction of Cuvier is his remarkable work in comparing extinct with recent organisms, his descriptions of the fossil Mammalia of the Paris basin, and his general application of the knowledge of recent animals to the reconstruction of extinct ones, as indicated by fragments only of their skeletons.
He showed (1830) that the organisms like Flustra are not hydroid Polyps, but of a more complex structure resembling Molluscs, and he gave them the name Polyzoa.
Van Beneden, Claparede, and Allman, who during the 19th century approached the study of the lower marine organisms in the same spirit as that in which Trembley and Schaffer in the 18th century, and Swammerdam in the 17th, gave themselves to the study of the minute fresh-water forms of animal life.
The most instructive classification of the " variations " exhibited by fully formed organisms consists in the separation in the first place of those which arise from antecedent congenital, innate, constitutional or germinal variations from those which arise merely from the operation of variation of the environment or the food-supply upon normally constituted individuals.
Why should we assume that it will be able to escape the moulding by environment (once its evoking cause is removed) to which, according to Lamarck's first law, all parts of organisms are subject ?
But practical necessity has given rise to the existence of many other divisions; see CYTOLOGY, for the structure of cells; EMBRYOLOGY, for the development of individual organisms; HEREDITY and REPRODUCTION, for the relations between parents and offspring.
II.); that is to say, it dies and falls a prey to the organisms which excite putrefaction, just as would happen to any other dead animal tissue were it unconnected with the body.
If the dead part be protected from the ingress of putrefactive organisms, however, it separates from that which is living without the ordinary evidences of gangrene, and is then known as an " aseptic slough."
If, on the other hand, any pathogenic organisms be present the results are disastrous because the tissue, deprived of its nervous trophic supply, has greatly lessened resistance.
From the histological examination of tumour cells there is no evidence to show that they resemble the protozoal unicellular organisms in occasionally passing through a sexual process of reproduction, i.e.
Thus Krawkow and Nowak, employing the frequent subcutaneous injection of the usual organisms of suppuration, have induced in the fowl the deposition within the tissues of a homogeneous substance giving the colour reactions of true amyloid.
Nowak, however, found later that he could generate it where the turpentine failed to induce suppuration; he believes that it may arise quite apart from the influence of the organisms of suppuration, that it is not a biological product of the micro-organisms of disease, and also that it has nothing to do with emaciation.
Now as our own bodies thus manipulate substances poisonous and antidotal, if in every hour of health we are averting selfintoxication, so likewise are we concerned with the various intruding organisms, whose processes of digestion are as dangerous as our own; if these destructive agents, which no doubt are incessantly gaining admission to our bodies, do not meet within us each its appropriate compensatory defensive agent, dissolution will begin.
of the crops grown upon it, it is now known to be a place of habitation for myriads of minute living organisms upon whose activity much of its fertility depends.
Much of the work carried on by these organisms is not clearly understood; there are, however, certain processes which have been extensively investigated and to these it is necessary to refer.
That: the action of living organisms is the cause of the production of nitrates is supported by the fact that the change does not occur when the soil is heated nor when it is treated with disinfectants which destroy or check the growth and life of bacteria.
The organisms do not carry on their work in soils deficient in air; hence the process is checked in water-logged soils.
It is the business of the farmer and gardener to promote the activity of these organisms by good tillage, careful drainage and occasional application of lime to soils which are deficient in this substance.
These organisms reduce nitrates to nitrites and finally to ammonia and gaseous free nitrogen which escapes into the atmosphere.
An important group of soil organisms are now known which have the power of using the free nitrogen of the atmosphere for the formation of the complex nitrogenous compounds of which their bodies are largely composed.
Later the nitrogen-content of the nodule decreases, most of the organisms, which are largely composed of proteid material, becoming digested and transformed into soluble nitrogenous compounds which are conducted to the developing roots and seeds.
In this manner organisms obtained from red clover can be grown and applied to the seed of red clover; and similar inoculation can be arranged for other species, so that an application of the bacteria most suited to the particular crop to be cultivated can be assured.
In many cases it has been found that inoculation, whether of the soil or of the seed, has not made any appreciable difference to the growth of the crop, a result no doubt due to the fact that the soil had already contained within it an abundant supply of suitable organisms. But in other instances greatly increased yields have been obtained where inoculation has been practised.
There is little doubt, however, that in the near future means will be devised to obtain the most efficient work from these minute organisms, either by special artificial cultivation and subsequent application to the soil, or by improved methods of encouraging their healthy growth and activity in the land where they already exist.
The destructive power of sunlight is only exercised on those organisms actually at the surface.
Their food consists of minute animal and vegetable organisms, (Redrawn by permission from Farmers Bulletin 155, Bureau of Ent., U.S. Dept.
They are flattened organisms provided with two or more suckers, hence their name (7 rpThµarc,8rls, pierced with holes), and are exclusively parasitic both in their earlier and mature stages of life.
These organisms live in cockles, oysters and other lamellibranchs and they so affect the gonads of these molluscs as to castrate and sterilize their host.
They are transparent leaf-like organisms and may often be found attached to the skin, mouth, nostrils or gills of fish; on the skin and bladder of Amphibia; and on those of certain Reptilia.
These are probably important in checking overgrowth by encrusting organisms, and in particular by preventing larvae from fixing on the zoarium.
Spencer welcomed the Darwinian theory, and enriched it with the phrase" survival of the fittest "; but he did not give up the (Lamarckian) belief in the hereditary transmission of the modifications of organisms by the exercise of function.
This exaggerates the passivity of life, and does not sufficiently recognize that the higher organisms largely adjust external to internal relations and adapt their environment to their needs.
And though Spencer's general position - that it is absurd to suppose that organisms after being modified by their life should give birth to offspring showing no traces of such modifications - seems the more philosophic, yet it does not dispose of the facts which go to show that most of the evidence for the direct transmission of adaptations is illusory, and that beings are organised to minimize the effects of life on the reproductive tissues, so that the transmission of the effects of use and disuse, if it occurs, must be both difficult and rare - far more so than is convenient for Spencer's psychology.
Some species, however, are alleged to be carnivorous, and a North American form of the genus Hydropsyche is said to spin around the mouth of its burrow a silken net for the capture of small animal organisms living in the water.
This idea originated in the discovery of a jelly-fish, gasteropods, and other organisms of a more or less marine type, and presenting some affinity with forms of Jurassic age.
Another stimulus came from the biologists, Pacific. On the 1st of November 1876 a cyclone acting in this who began to realize the importance of a more detailed investigaway submerged a great area of the level plain of the Ganges tion of the life conditions of organisms at great depths in the delta to a depth of 46 ft.; here the influence of the difference sea.
5) collection of the organisms of the deep sea.
Pure calcareous sand and calcareous mud are formed by wave action on the shores of coral islands where the only material available is coral and the accompanying calcareous algae, crustacea, molluscs and other organisms secreting carbonate of lime.
Recent limestones are being produced in this way and also in some places by the precipitation of calcium carbonate by sodium or ammonium carbonate which has been carried into the sea or formed by organisms. The precipitated carbonate may agglomerate on mineral or organic grains which serve as nuclei, or it may form a sheet of hard deposit on the bottom as occurs in the Red Sea, off Florida, and round many coral islands in the Pacific. Only the sand and the finest-grained sediments of the shore zone are carried outwards over the continental shelf by the tides or by the reaction-currents along the bottom set up by on-shore winds.
Sand may be taken as the predominating deposit on the continental shelves, often with a large admixture of remains of calcareous organisms, for instance the deposits of marl made up of nullipores off the coasts of Brittany and near Belle Isle.
The proportion of calcium carbonate varies greatly according to the amount of foraminifera and other calcareous organisms which it contains.
When the proportion of calcium carbonate in the blue mud is considerable there results a calcareous ooze, which when found on the continental slope and in enclosed seas is largely composed of remains of deep-sea corals and bottom-living foraminif era, pelagic organisms including pteropods being less frequently represented.
To this inconceivably slowly-growing deposit of inorganic material over the ocean floor there is added an overwhelmingly more rapid contribution of the remains of calcareous and siliceous planktonic and benthonic organisms, which tend to bury the slower accumulating material under a blanket of globigerina, pteropod, diatom or radiolarian ooze.
Pettersson in 1894, two portions of sea-water are collected in glass tubes which have been exhausted of air, coated internally with mercuric chloride to prevent the putrefaction of any organisms, and sealed up beforehand.
The whole ocean must thus form but a cold dwelling-place for the organisms of the deep sea.
The differences of salinity support this method, and, especially in the northern European seas, often prove a sharper criterion of the boundaries than temperature itself; this is especially the case at the entrance to the Baltic. Evidence drawn from drift-wood, wrecks or special drift bottles is less distinct but still interesting and often useful; this method of investigation includes the use of icebergs as indicators of the trend of currents and also of plankton, the minute swimming or drifting organisms so abundant at the surface of the sea.
But whatever merits they had as clarifiers of turbid water, the advent of bacteriology, and the recognition of the fact that the bacteria of certain diseases may be water-borne, introduced a new criterion of effectiveness, and it was perceived that the removal of solid particles, or even of organic impurities (which were realized to be important not so much because they are dangerous to health per se as because their presence affords grounds for suspecting that the water in which they occur has been exposed to circumstances permitting contamination with infective disease), was not sufficient; the filter must also prevent the passage of pathogenic organisms, and so render the water sterile bacteriologically.
They are ridges of aeolian limestone plastered over by a thin layer of corals and other calcareous organisms. The very remarkable "serpuline atolls" are covered by a solid crust made of the convoluted tubes of serpulae and Vermetus, together with barnacles, mussels, nullipores, corallines and some true incrusting corals.
The products of the decay of the organisms thus A, Bladder of Utricularia neglecta (after Darwin), enlarged.
The Hydrozoa comprise the hydroids, so abundant on all shores, most of which resemble vegetable organisms to the unassisted eye; the hydrocorallines, which, as their name implies, have a massive stony skeleton and resemble corals; the jelly-fishes so called; and the Siphonophora, of which the species best known by repute is the so-called "Portuguese man-of-war" (Physalia), dreaded by sailors on account of its terrible stinging powers.
Cholera and typhoid organisms are less resistant, and are killed more quickly than tubercle bacilli at the above temperatures.
It is imperative that cream destined for butter-making should be free from pathogenic organisms.
From a study of remains of the mollusca, brachiopoda and other marine organisms they will determine the shallow water (littoral) and deep water (abyssal) regions of the surrounding oceans, and the clear or muddy, salt, brackish or fresh character of its inland and marginal seas; and even the physical conditions of the open sea at the time will be ascertained.
The selection of organisms through the crucial test of fitness and the shaping of the organic world is an orderly process when contemplated on a grand scale.
Medusae capture their prey, consisting of small organisms of various kinds, especially Crustacea, by means of the tentacles which hang out like fishing-lines in all directions.
A great variety of forms were described by other observers, but they were not separated as a class from the unicellular organisms (Protozoa) with which they usually occur, until the appearance of C. G.
Widely divergent forms make their appearance suddenly in the Cambrian period amongst the earliest known fossils; and the high perfection of structure to which they had at that time attained Let a = We have also (31) n2x2 y (I implies the antecedent existence of much simpler types, and refers the origin of life to a date immeasurably distant from that at which we have actual proof of the existence of animal and vegetable organisms.
There is very little doubt that they lived at the bottom of the sea, feeding upon worms or other soft marine organisms, crawling slowly about the sandy or muddy bottom and burying themselves beneath its surface when danger threatened.
Of late years considerable progress has taken place in our knowledge of these organisms, research upon them having been stimulated by the realization of their extreme importance in medical parasitology.
Castellani (6) found the organisms (most probably the same species) in the cerebro-spinal fluid of patients suffering from sleeping-sickness in Uganda; and it has since been conclusively proved by Sir David Bruce and D.
On gaining an entry into the blood of a vertebrate the organisms pass rapidly into the general circulation, and are thus carried all over.
In the one case they are entirely restricted to the neighbourhood of the boil or ulcer, whereas in the other there is a general infection of the body, the organisms spreading to all parts and being met with in the spleen, liver, bone-marrow, &c., and (rarely) in the peripheral circulation.
plicatilis (the type-species of Ehrenberg) and other forms (51), he finds, however, that this is not the case, but that the organisms exemplified by S.
Rogers," On the development of flagellated organisms (Trypanosomes) from the spleen Protozoic parasites of cachexial fevers and Kala-azar," Quart.
He was an active worker in physiological chemistry, and carried out many analyses of the products of living organisms, among them being one of the gastric juice which, at the end of 1823, resulted in the notable discovery that the acid contents of the stomach contain hydrochloric acid which is separable by distillation.
The later Western Manichaeans termed those portions of light which are scattered throughout the world - in its elements and organisms - awaiting their deliverance, the Jesus patibilis.
At the southern end of the peninsula is a series of coral islands, known as keys; they appear to be due to the forward growth of corals and other lime-secreting organisms towards the strong current of the Gulf Stream, by which their food is supplied:
thick and said to be made up largely of the secretions of organisms. Such thicknesses of such material go far to modify the former opinion that the Tertiary periods were short.
The food of the Anodonta, as of other Lamellibranchs, consists of microscopic animal and vegetable organisms, brought to the mouth by the stream which sets into the sub-pallial chamber at the lower siphonal notch (e in fig.
Ten years later he replaced the name " Zoophyta " by " Mollusca," which was thus in the first instance applied, not to the Mollusca at present so termed, but to a group consisting chiefly of other organisms. Gradually, however, the term Mollusca became used to include those Mollusca formerly placed among the " Testacea," as well as the naked Mollusca.
Pasteur showed that the origin of the disease proceeded from microscopic organisms called ferments and vitrios.
In effect (6) it traces the Turbellaria to small two-layered organisms consisting of an outer ciliated epidermis and a central syncytial tissue.
Aristotle had imputed to all living beings a soul, though to plants only in the sense of a vegetative, not a sensitive, activity, and in Moleschott's time many scientific men still accepted some sort of vital principle, not exactly soul, yet over and above bodily forces in organisms. Moleschott, like Lotze, not only resisted the whole hypothesis of a vital principle, but also, on the basis of Lavoisier's discovery that respiration is combustion, argued that the heat so produced is the only force developed in the organism, and that matter therefore rules man.
He supposes that all organisms have developed from the simple cell, and that this has its origin by spontaneous generation, to explain which he propounds the " carbon-theory," that protoplasm comes from inorganic carbonates.
Hence, when he returns to organisms, it does not surprise us that he assigns to ova and spermatozoa cell-souls, to the impregnated ovum germ-soul, to plants tissue-souls, to animals nerve-souls; or that he regards man's body and soul as born together in the impregnated ovum, and gradually evolved from the bodies and souls of lower animals.
He supposes that this evolution does not remain cosmic, but becomes organic. In accordance with Lamarck's hypothesis, he supposes an evolution of organisms by hereditary adaptation to the environment (which he considers necessary to natural selection), and even the possibility of an evolution of life, which, according to him, is the continuous adjustment of internal to external relations.
He throws out the brilliant suggestion that the experience of the race is in a sense inherited by the individual; which is true in the sense that animal organisms become hereditarily better adapted to perform mental operations, though no proof that any elements of knowledge become a priori.
Shall we resign our traditional belief that the greater part of the world is mere body, but that its general adaptability to conscious organisms proves its creation and government by God, and take to the new hypothesis, which, by a transfer of design from God to Nature, supposes that everything physical is alive, and conducts its life by psychical impulses of its own?
Wundt supposes not only that all organisms have outer will, the will to act, but also that all thinking is inner will - the will to think.
According to him, that which acts in all organisms, that which acts in all thinking, that which divides unitary experience into subject and object, the source of self-consciousness, the unity of our mental life, " the most proper being of the individual subject is will."
On the whole, his voluntarism, though like that of Schopenhauer and Hartmann, is not the same; not Schopenhauer's, because the ideating will of Wundt's philosophy is not a universal irrational will; and not Hartmann's, because, although ideating will, according to Wundt's phenomenalism, is supposed to extend through the world of organisms, the whole inorganic world remains a mere object of unitary experience.
Darwin said, given that organisms are fit, they will tend to survive; but he failed to show how they become fit.
Leuckhart to a small group of transparent and for the most part pelagic organisms, whose position in the animal kingdom is a very isolated one.
As organisms rise higher in the scale of development, the sharper and more distinct become their outlines, the more definite their individualities.
Although, like protective resemblance, quite independent of affinity between the organisms concerned in the likeness, mimicry occurs most commonly between animals structurally similar, and therefore related, to one another, the relationship may be close or remote.
LICHENS, in botany, compound or dual organisms each consisting of an association of a higher fungus, with a usually unicellular, sometimes filamentous, alga.
Until comparatively recent times the lichens were considered as a group of simple organisms on a level with algae and fungi.
Theoretically the lichens may be classified on the basis of their algal constituent, on the basis of their fungal constituent, or they may be classified as if they were homogeneous organisms. The first of these systems is impracticable owing to the absence of algal reproductive organs and the similarity of the algal cells (gonidia) in a large number of different forms. The second system is the most obvious one, since the fungus is the dominant partner and produces reproductive organs.
The general relation between parent and filial organisms is discussed under Heredity and Embryology; many of the details of the cellular processes are dealt with under Cytology, and the modes of reproduction exhibited by different kinds of animals and plants are treated of in the various articles describing individual groups.
Respiration in plants, as in other organisms, is a process that goes on by night as well as by day and consists in plants in the breaking up of the complex carbonaceous substances formed by assimilation into less complex and more transportable substances.
The groups of organisms utilized for zoning and correlation by different workers include brachiopods, pelecypods, cephalopods, corals, fishes and plants; and the results of the comparison of the faunas and floras of different areas where Carboniferous rocks occur are generalized in the table below.
Thus western Europe in early Carboniferous time was occupied by a series of constricted, gulf-like seas; and on account of the steady progress of intermittent warping movements of the crust, we find that the areas of clearer water, in which the limestone-building organisms could exist, were repeatedly able to spread, thus forming those thin limestones found interbedded with shale and sandstone which occur typically in the Yoredale district of Yorkshire and in the region to the north, and also in the culm deposits of central Europe.
These they obtain usually in the form of carbohydrates from the dead remains of other organisms, or in this or other forms from the living cells of their hosts; in the former case they are termed saprophytes, in the latter parasites.
It was formerly the custom to include with the Fungi the Schizomycetes or Bacteria, and the Myxomycetes or Mycetozoa; but the peculiar mode of growth and division, the cilia, spores and other peculiarities of the former, and the emission of naked amoeboid masses of protoplasm, which creep and fuse to streaming plasmodia, with special modes of nutrition and spore-formation of the latter, have led to their separation as groups of organisms independent of the true Fungi.
On the other hand, lichens, previously regarded as autonomous plants, are now known to be dual organisms - fungi symbiotic with algae.
As regards their geographical distribution, fungi, like flowering plants, have no doubt their centres of origin and of dispersal; but we must not forget that every exchange of wood, wheat, fruits, plants, animals, or other commodities involves transmission of fungi from one country to another; while the migrations of birds and other animals, currents of air and water, and so forth, are particularly efficacious in transmitting these minute organisms. Against this, of course, it may be argued that parasitic forms can only go where their hosts grow, as is proved to be the case by records concerning the introduction of Puccinia malvacearum, Peronospora viticola, Hemileia vastatrix, &c. Some fungi - e.g.
Although many fungi have been regarded as devoid of nuclei, and all have not as yet been proved to contain them, the numerous investigations of recent years have revealed them in the cells of all forms thoroughly examined, and we are justified in concluding that the nucleus is as essential to the cell of a fungus as to that of other organisms. The hyphae of many contain numerous, even hundreds of nuclei (Phycomycetes); those of others have several (Aspergillus) in each segment, or only two (Exoascus) or one (Erysiphe) in each cell.
The group has attained an importance of late even beyond that to which it was brought by Pasteur's researches on alcoholic fermentation, chiefly owing to the exact results of the investigations of Hansen, who first applied the methods of pure cultures to the study of these organisms, and showed that many of the inconsistencies hitherto existing in the literature were due to the coexistence in the cultures of several species or races of yeasts morphologically almost indistinguishable, but physiologically very different.
The various cells of these organisms are connected by large pits which are traversed by thick protoplasmic threads connecting one cell with the next.
Here you find articles in the encyclopedia about single-celled organisms.
Teleology, in this narrower sense, as the study of the adaptation of organic structures to the service of the organisms in which they occur, was completely revolutionized by Darwinism and the research founded on it.
These grooves doubtless serve to direct currents of water, carrying with them small organisms towards the mouth.
Of these the first three include multicellular plants, some of them of great size; the last three are unicellular organisms, with little in common with the rest excepting the possession of a brown colouring matter.
The organisms constituting this plankton are mostly unicellular, of ten aggregated together in colonies, and the remarkable structure which they exhibit has added a new chapter to the story of adaptation to environment.
Traces of annelids and probably other organisms have been found in the bands of shale occurring in the south-west of the shire of Ross and Cromarty, in the isle of Raasay, and at Cailleach Head, and are the oldest relics of animal life yet found in Great Britain.
Living organisms vary, that is to say, no two individuals are exactly alike; the death-rate and the multiplication-rate are to a certain extent selective, that is to say, on the average, in the long run, they favour certain variations and oppress other variations.
Buffon, in a cautious, tentative fashion, suggested rather than stated the mutability of species and the influence of the forces of nature in moulding organisms. Immanuel Kant, in his Theory of the Heavens (1755), foreshadowed a theory of the development of unformed matter into the highest types of animals and plants, and suggested that the gradations of structure revealed by comparative anatomy pointed to the existence of blood relationship of all organisms, due to derivation from a common ancestor.
He appeared to believe, however, that the successive variations and modifications had arisen in response to mechanical laws of the organisms themselves rather than to the influence of their surroundings.
Robert Chambers, in the once famous Vestiges of Creation, interested and shocked his contemporaries by his denial of the fixity of species and his insistence on creation by progressive evolution, but had no better theory of the cause of variation than to suppose that organisms - "from the simplest and oldest to the highest and most recent" were possessed of "an inherent impulse, imparted by the Almighty both to advance them from the several grades and modify their structure as circumstances required."
He insisted that the great powers of increase of all organisms led to a tremendous struggle for existence, and that variability extended to every part and organ of every organism; that the variability was large in amount in proportion to the size of the part affected, and occurred in a considerable proportion of the individuals of those large and dominant species which might be supposed to be breaking up into new species.
He pointed to the changes wrought on domesticated organisms by the artificial selection of similar variations, and drew the inference that there must be parallel occurrences under wild nature.
Wallace, whilst insisting that the range of observed and measured variation was much larger in proportion to the size of the organisms or parts of organism affected than was generally believed, leaned to the Darwinian view in excluding from the normal factors in the origin of species variations of the extremer ranges of magnitude.
Successful organisms, or well-adapted organisms, are those that have responded to the environment, whether by large or small variations, in suitable fashion.
Much of the character of organisms is due to various symmetries, radial, bilateral, metameric and so forth, and these symmetries arise, partly at least, from the mode of growth by cell division and the marshalling of groups of cells to the places where they are destined to proliferate.
The series into which we can arrange the results of observing phenomena of complex causation, whether exhibited by living organisms or not, have certain properties in common, which are dealt with by the theory of chance.
The past history of the organic world displays many successful series and these, as they have survived, must inevitably display orthogenesis to some extent; but it also displays many failures which indeed may be regarded as showing that the limitation of variation has been such that the organisms have lost the possibility of successful response to a new environment.
In the broadest way variation in organisms is primarily the necessary result of the absence of uniformity in the distribution of physical forces on the globe, in fact is a mere necessary response to the variation of inorganic conditions.
antiquity disappeared; and how the only living organisms were vassalage and clientship. The second volume, Les Origines communales, la feodalite et la chevalerie (1893), deals with the reconstruction of society on new bases which took place in the 10th and 11th centuries.
The fossils from the Rhaetic beds belong to the Avicula contorta zone, those from the Lias to the Ammonites angulatus zone, while the blocks of limestone with chert contain Inoceramus, Cretaceous foraminifera and other organisms. The materials yielding these fossils are embedded in a course volcanic agglomerate which gives rise to crags and is pierced by acid and basic igneous ricks.
In a general survey of the life of this period, as it is revealed by the fossils, three outstanding facts are apparent: (I) the great divergence between the Cambrian fauna and that of the present day; (2) the Cambrian life assemblage differs in no marked manner from that of the succeeding Ordovician and Silurian periods; there is a certain family likeness which unites all of them; (3) the extraordinary complexity and diversity not only in the assemblage as a whole but within certain limited groups of organisms. Although in the Cambrian strata we have the oldest known fossiliferous rocks - if we leave out of account the very few and very obscure organic remains hitherto recorded from the pre-Cambrian - yet we appear to enter suddenly into the presence of a world richly peopled with a suite of organisms already far advanced in differentiation; the Cambrian fauna seems to be as far removed from what must have been the first forms of life, as the living forms of this remote period are distant from the creatures of to-day.
Its food consists of microscopic organisms and organic particles; these are drawn into the mouth FIG.
Both, too, were spiritual and elastic tendencies toward progress, ideals rather than solid organisms.
In view of the fact that fresh grape juice contains innumerable bacteria and moulds, in addition to the yeast cells which bring about the alcoholic fermentation, and that the means which are adopted by the brewer and the distiller for checking the action of these undesirable organisms cannot be employed by the wine-maker, it is no doubt remarkable that the natural wine yeast so seldom fails to assert a preponderating action, particularly as the number of yeast cells at the beginning of fermentation is relatively small.
The fact is that the constitution of average grape juice and the temperatures of fermentation which generally prevail are particularly well suited to the life action of wine yeast, and are inimical to the development of the other organisms. When these conditions fail, as is, for instance, the case when the must is lacking in acidity, or when the weather during the fermentation period is very hot and means are not at hand to cool the must, bacterial side fermentations may, and do, often take place.
Wortmann examined a number of old wines and found that in all cases in which the wine was still in good condition or of fine character a small number of living organisms (yeast cells, &c.) were still present.
the Jews are forbidden to eat animals other than cloven-footed ruminants; thus the camel, coney, hare and swine were forbidden; so also any water organisms that had not fins and scales, and a large choice of birds, including swan, pelican, stork, heron and hoopoe.
It has been shown bï¿½arwin that, in the case of most animals and plants in a state of nature, the competition of other organisms is a tar more efficient agency in limiting their distribution than the mere influence of climate.
The surface of the skin may be invaded by parasitic organisms and may exhibit spots, which are removed by something which will destroy the parasite, such as ointments containing mercurial salts.
The minute organisms which are commonly called " bacteria " 1 are also known popularly under other designations, e.g.
THE Study Of Bacteria The general advances which have been made of late years in the study of bacteria are clearly brought to mind when we reflect that in the middle of the 19th century these organisms were only known to a few experts and in a few forms as curiosities of the microscope, chiefly interesting for their minuteness and motility.
They were then known under the name of " animalculae," and were confounded with all kinds of other small organisms. At that time nothing was known of their life-history, and no one dreamed of their being of importance to man and other living beings, or of their capacity to produce the profound chemical changes with which we are now so familiar.
The schizomycetes or bacteria are minute vegetable organisms devoid of chlorophyll and multiplying by repeated bipartitions.
Plants appear to be less subject to their attacks - possibly, as has been suggested, because the acid fluids of the higher vegetable organisms are less suited for the development of Schizomycetes; nevertheless some are known to be parasitic on plants.
Little was known about these extremely minute organisms before 1860.
Cohn's brilliant researches, the chief results of which were published at various periods between 1853 and 1872; Cohn's classification of the bacteria, published in 1872 and extended in 1875, has in fact dominated the study of these organisms almost ever since.
In the meantime, while various observers were building up our knowledge of the morphology of bacteria, others were laying the foundation of what is known of the relations of these organisms to fermentation and disease - that ancient will-o'-the-wisp " spontaneous generation " being revived by the way.
When Pasteur in 1857 showed that the lactic fermentation depends on the presence of an organism, it was already known from the researches of Schwann (1837) and Helmholtz (1843) that fermentation and putrefaction are intimately connected with the presence of organisms derived from the air, and that the preservation of putrescible substances depends on this principle.
In the first place, the ancient question of " spontaneous generation " received fresh impetus from the difficulty of keeping such minute organisms as bacteria from reaching and developing in organic infusions; and, secondly, the long-suspected analogies between the phenomena of fermentation and those of certain diseases again made themselves felt, as both became better understood.
Needham in 1745 had declared that heated infusions of organic matter were not deprived of living beings; Spallanzani (1777) had replied that more careful heating and other precautions prevent the appearance of organisms in the fluid.
Various experiments by Schwann, Helmholtz, Schultz, Schroeder, Dusch and others led to the refutation, step by step, of the belief that the more minute organisms, and particularly bacteria, arose de novo in the special cases quoted.
The difficult subject of the classification of bacteria dates ' The difficulties presented by such minute and simple organisms as the Schizomycetes are due partly to the few " characters " which they possess and partly to the dangers of error in manipulating them; it is anything but an easy matter either to trace the whole development of a single form or to recognize with certainty any one stage in the development unless the others are known.
This being the case, and having regard to the minuteness and ubiquity of these organisms, we should be very careful in accepting evidence as to the continuity or otherwise of any two forms which falls short of direct and uninterrupted observation.
In Migula's scheme the attempt is made to avoid some of these difficulties, but others are introduced by his otherwise clever devices for dealing with these puzzling little organisms.
The vast majority of these organisms are not pathogenic, most are harmless and 4.,52 5.20 5.20 FIG.
These forms are termed by Fischer Metatrophic, because they require various kinds of organic materials obtained from the dead remains of other organisms or from the surfaces of their bodies, and can utilize and decompose them in various ways (Polytrophic) or, if monotrophic, are at least unable to work them up. The true parasites - obligate parasites of de Bary - are placed by Fischer in a third biological group, Paratrophic bacteria, to mark the importance of their mode of life in the interior of living organisms where they live and multiply in the blood, juices or tissues.
Fresh manure abounds in de-nitrifying bacteria, and these organisms not only reduce the nitrates to nitrites, even setting free nitrogen and ammonia, but their effect extends to the undoing of the work of what nitrifying bacteria may be present also, with great loss.
The combined nitrogen of dead organisms, broken down to ammonia by putrefactive bacteria, the ammonia of urea and the results of the fixation of free nitrogen, together with traces of nitrogen salts due to meteoric activity, are thus seen to undergo various vicissitudes in the soil, rivers and surface of the globe generally.
In many cases the colour-production is dependent on certain definite conditions - temperature, presence of oxygen, nature of the food-medium, &c. Ewart's important discovery that some of these lipochrome pigments occlude oxygen, while others do not, may have bearings on the facultative anaerobism of these organisms.
A branch of bacteriology which offers numerous problems of importance is that which deals with the organisms so common in milk, butter and cheese.
Milk is a medium not only admirably suited to the growth of bacteria, but ry Y Y g as a matter of fact, always contaminated with these organisms in the ordinary course of supply.
It is these bacteria which form the zoogloea of the " mother of vinegar," though this film may contain other organisms as well.
The idea that this film of bacteria oxidizes the alcohol beneath by merely condensing atmospheric oxygen in its interstices, after the manner of spongy platinum, has long been given up; but the explanation of the action as an incomplete combustion, depending on the peculiar respiration of these organisms - much as in the case of nitrifying and sulphur bacteria - is not clear, though the discovery that the acetic bacteria will not only oxidize alcohol to acetic acid, but further oxidize the latter to CO 2 and 01-1 2 supports the view that the alcohol is absorbed by the organism and employed as its respirable substance.
W.) which Arloing, Buchner, Chmelewski, and others took part, have led to the proof that rays of light alone are quite capable of killing these organisms. The principal questions were satisfactorily settled by Marshall Ward's experiments in 1892-1893, when he showed that even the spores of B.
The principal experiments also indicate that it is the rays of highest refrangibility - the blue-violet and ultra-violet rays of the spectrum - which bring about the destruction of the organisms (figs.
This phenomenon is due to the activity of a whole series of marine bacteria of various genera, the examination and organisms depend on the discovery that their patho genicity or virulence can be modified - diminished or increased - by definite treatment, and, in the natural course of epidemics, by alterations in the environment.
the Sereh disease of the sugar-cane, the slime fluxes of oaks and other trees, are not only very doubtful cases, in which other organisms such as yeasts and fungi play their parts, but it may be regarded as extremely improbable that the bacteria are the primary agents at all; they are doubtless saprophytic forms which have gained access to rotting tissues injured by other agents.
Nencki showed, however, that if both these organisms occur together, the resulting products contain large quantities of normal butyl alcohol, a substance neither bacterium can produce alone.
fermentations induced by them, the resistance of their spores to dessication, heat, &c. - but it is worth while to ask how far these properties are really remarkable when all the data for comparison with other organisms are considered.
In the first place, the extremely small size and isolation of the vegetative cells place the protoplasmic contents in peculiarly favourable circumstances for action, and we may safely conclude that, weight for weight and molecule for molecule, the protoplasm of bacteria is brought into contact with the environment at far more points and over a far larger surface than is that of higher organisms, whether - as in plants - it is distributed in thin layers round the sap-vacuoles, or - as in animals - is bathed in fluids brought by special mechanisms to irrigate it.
- A plate-culture colony of a in more complex multispecies of Bacillus - Proteus (Hauser) cellular organisms. To - on the fifth day.
Thus the organisms of suppuration, tubercle, glanders, diphtheria, typhoid fever, cholera, tetanus, and others were identified, and their relationship to the individual diseases established.
The laws of passive immunity were shown to hold also in the case of immunity against living organisms by R.
In this case a general reaction is stimulated by the vaccine which may aid in the destruction of the invading organisms. In regulating the administration of such vaccines he has introduced the method of observing the opsonic index, to which reference is made below.
Of the discoveries of new organisms the most important is that of the Spirochaete pallida in syphilis by Schaudinn and Hoffmann in 1905; and although proof that it is the cause of the disease is not absolute, the facts that have been established constitute very strong presumptive evidence in favour of this being the case.
The general principle in their preparation is to supply cutt;va- the nutriment for bacterial growth in a form as nearly g y similar as possible to that of the natural habitat of the organisms - in the case of pathogenic bacteria, the natural fluids of the body.
As our knowledge has advanced it has become abundantly evident that the so-called pathogenic bacteria are not organisms with special features, but that each is a member of a group of organisms possessing closely allied characters.
It is to be noted that in the case of bacteria we can only judge of organisms being of different species by the stability of the characters which distinguish them, and numerous examples might be given where their characters become modified by comparatively slight change in their environment.
In the first place, such organisms may be differentiated by the chemical change produced by them in various culture media, e.g.
The modes of cultivation described apply only to organisms which grow in presence of oxygen.
The fact that in anthrax, one of the first diseases to be fully studied, numerous bacilli are present in the blood of infected animals, gave origin to the idea that the organisms might produce their effect by using up the oxygen g ' P Y g P Yg of the blood.
In many cases, however, the filtrate, when injected, produces comparatively little effect, whilst toxic action is observed when the bacteria in a dead condition are used; this is the case with the organisms of tubercle, cholera, typhoid and many others.
A considerable amount of work has been done in connexion with this subject, and many observers have found that fluids taken from the living body in which the organisms have been growing, contain toxic substances, to which the name of aggressins has been applied.
the multiplication of the living organisms in the tissues; this is essential to, and regulates, the supply of toxins.
It is important that these two essential factors should be kept clearly in view, since the means of defence against any disease may depend upon the power either of neutralizing toxins or of killing the organisms producing them.
It is to be noted that there is no fixed relation between toxin production and bacterial multiplication in the body, some of the organisms most active as toxin producers having comparatively little power of invading the tissues.
in the human subject, often due to streptococci, the process is similar, but the organisms are found especially in the capillaries of the internal organs and may not be detectable in the peripheral circulation during life.
In another class of diseases, the organisms. first produce some well-marked local lesion, from which secondary extension takes place by the lymph or blood stream to other parts of the body, where corresponding lesions are formed.
It is also probable that in a state of health organisms do gain entrance to the blood from time to time and are rapidly killed off.
at higher temperatures than the optimum, in the presence of weak antiseptics, &c. The virulence of many organisms, however, becomes diminished when they are grown on the ordinary artificial media, and the diminution is sometimes accelerated by passing a current bility.
in the peritoneum, by injections of nonpathogenic organisms, peptone, nucleic acid and various other substances.
Wright and Douglas showed that under these conditions phagocytosis might occur when a small quantity of normal serum was present, whereas it was absent when normal salt solution was substituted for the serum; the latter thus contained substances which made the organisms susceptible to the action of the phagocytosis.
They further showed that this substance acted by combining with the organisms and apparently producing some alteration in them; on the other hand it had no direct action on the leucocytes.
On the contrary the labile opsonins of normal serum have a comparatively general action on different organisms. It is quite evident that the specific immune-opsonins may play a very important part in the phenomena of immunity, as by their means the organisms are taken up more actively by the phagocytic cells, and thereafter may undergo rapid disintegration.
The principle in such treatment by means of vaccines is to stimulate the general production of anti-substances throughout the body, so that these may be carried to the sites of bacterial growth, and aid the destruction of the organisms by means of the cells of the tissues.
Variations in chemiotaxis towards different organisms probably depend in natural conditions, as well as in active immunity, upon the opsonic content of the serum.
by sensitiveness to chemical substances in their surroundings - a property which is not peculiar to them but is possessed by various unicellular organisms, including motile bacteria.
This single cavity and its lining serve apparently for all those functions (digestion, excretion, circulation and often reproduction) which in more complex organisms are distributed among various cavities of independent and often very diverse origin.
Matter and the sensible universe are the relations between particular organisms, that is, mind organized into consciousness, and the rest of the world.
The family, the tribe, the city, the simpler and more complex organisms of the Hellenic polity, were specially under his care and direction.
They are chiefly pelagic organisms, floating at or near the surface of the water, but occur also at great depths, and are sometimes fixed and sessile in habit.
The muscle-bands are very contractile, rendering the scyphistoma one of the most difficult of all organisms to preserve in an expanded condition.
Some of the boulders are encrusted by marine organisms and must have been dropped by icebergs in the sea.
As in many other " pelagic " organisms, spines and processes from the surface of the body are often developed, which are probably less important as defensive organs than as aids to flotation.
- Scaphopoda feed on the lowest marine organisms such After Kowalewsky, in Lanas Diatoms, Protozoa, &c. There are 150 's Treatise on Zoology, living and about 275 known fossil species.
He compared the fossil with the living organisms, and distinguished marine and fiuviatile formations.
The definition of life must really be a description of the essential characters of life, and we must set out with an investigation of the characters of living substance with the special object of detecting the differences between organisms and unorganized matter, and the differences between dead and living organized matter.
We must now examine in more detail the differences which exist or have been alleged to exist between living organisms and inorganic bodies.
Most living bodies, it is true, are capable of reproduction, but there are many without this capacity, whilst, on the other hand, it would be difficult to draw an effective distinction between that reproduction of simple organisms which consists of a sub-division of their substance with consequent resumption of symmetry by the separate pieces, and the breaking up of a drop of mercury into a number of droplets.
In less highly integrated organisms, such as "cold-blooded" vertebrates, the point of death is less conspicuous, and when we carry our observations further down the scale of animal life, there ceases to be any salient phase in the slow transition from life to death.
By means of the stinging nettle-cells or nematocysts with which the tentacles are thickly covered, living organisms of various kinds are firmly held and at the same time paralysed or killed, and by means of longitudinal muscular fibrils formed from the cells of the ectoderm the tentacles are contracted and convey the food to the mouth.
The name polyp was given to these organisms from their supposed resemblance to an octopus.
The sand, which is nominally the filter, has interstices about thirty times as wide as the largest dimensions of the larger microbes; and the reason why these, and, still more, why organisms which were individually invisible under any magnifying power, and could only be detected as colonies, were arrested, was not understood.
Both these filters arrest the organisms by purely mechanical action, and if the joints are water-tight and they receive proper attention and frequent sterilization, they both give satisfactory results on a small scale for domestic purposes.
ABIOGENESIS, in biology, the term, equivalent to the older terms "spontaneous generation," Generatio aequivoca, Generatio primaria, and of more recent terms such as archegenesis and archebiosis, for the theory according to which fully formed living organisms sometimes arise from not-living matter.
From the 17th century onwards it was gradually shown that, at least in the case of all the higher and readily visible organisms, abiogenesis did not occur, but that omne vivum e vivo, every living thing came from a pre-existing living thing.
van Leeuwenhoek discovered bacteria, and it was soon found that however carefully organic matter might be protected by screens, or by being placed in stoppered receptacles, putrefaction set in, and was invariably accompanied by the appearance of myriads of bacteria and other low organisms. As knowledge of microscopic forms of life increased, so the apparent possibilities of abiogenesis increased, and it became a tempting hypothesis that whilst the higher forms of life arose only by generation from their kind, there was a perpetual abiogenetic fount by which the first steps in the evolution of living organisms continued to arise, under suitable conditions, from inorganic matter.
It may now be stated definitely that all known living organisms arise only from pre-existing living organisms.
It must be noted, however, that this disproof relates only to known existing organisms. All these are composed of a definite substance, known as protoplasm, and the modern refutation of abiogenesis applies only to the organic forms in which protoplasm now exists.
The Graptoloidea have also been regarded by some as benthonic organisms. A more prevalent view, however, is that the majority were pseudo-planktonic or drifting colonies, hanging from the underside of floating seaweeds; their polyparies being each .suspended by the nema in the earliest stages of growth, and, in later stages, some by the nemacaulus, while others became adherent above by means of a central disk or by parts of their dorsal walls.
One of the most extraordinary and persistent myths of medieval natura history, dating back to the 12th century at least, was the cause of transferring to these organisms the name of the barnack or bernacle goose (Bernicla branta).
It is an interesting and important fact that the newly hatched young of certain species, Margaropus annulatus for instance, before it has fed, if produced by a female carrying the germs of spirillosis, can infect healthy organisms with the disease.
The skeletons of many other organisms, such as Polyzoa and Mollusca, contribute to coral masses but cannot be included in the term "coral."
- Wheat, like other cereals, is liable to epidemic diseases caused by parasitic organisms which prey on the plant tissues.
With regard to the bacillary type, at first both organisms were considered to be identical, and the name bacillus dysenteriae was given to them; but later it was shown that these bacilli are different, both in regard to their cultural characteristics and also in that one (Shiga) gives out a soluble toxin, whilst the other has so far resisted all efforts to discover it.
Spicules of sponges and fragments of other organisms, such as molluscs, polyzoa, foraminifera and brachiopods, often occur in flint, and may be partly or wholly silicified with retention of their original structure.
The process has been very gradual and the organisms of the original chalk often have their outlines preserved in the flint.
The former view is based on the existence in the lake of organisms of a decidedly marine type.
The remains of the plants of former periods, which have come down to us in the fossilized state, are almost always fragmentary, and often imperfectly preserved; but their investigation is of the utmost importance to the botanist, as affording the only direct evidence of the past history of vegetable organisms. Since the publication of the Origin of Species the general acceptance of the doctrine of evolution has given a vastly increased significance to palaeontological data.
The determination of the course of descent has now become the ultimate problem for the systematist: this is an historical question, and the historical documents available are the remains of the ancient organisms preserved in the rocks.
There can be no doubt that the verticillate Siphoneae, a group much isolated among recent organisms, are among the most ancient families of plants.
It may appear surprising that a body containing 65% of carbon should be so largely made up of gelatinous Algae in a comparatively little altered condition, but the material is rich in bitumen, which seems to have replaced the water contained in the organisms when alive.
This it is obvious must commonly be the case, as most leaves and fruits are not calculated to drift far in the sea without injury or in abundance; nor are they likely as a rule to be associated with marine organisms. Deposits containing marine fossils can be compared even when widely separated, for the ocean is continuous and many marine species are world-wide.
Pharmacology is a branch of biology; it is also closely connected with pathology and bacteriology, for certain drugs produce structural as well as functional changes in the tissues, and in germ diseases the peculiar symptoms are caused by foreign substances (toxins) formed by the infective organisms present in the body.
Locally their destructive and irritating effects vary a good deal, but even when very dilute they all have a marked poisonous action on bacteria, white blood corpuscles, yeast and similar organisms. After absorption most of them exercise a depressing effect upon the nervous system, and are capable of reducing high temperature.
The cinchona alkaloids have a specifically poisonous effect on the parasites of malaria when present in human blood, and are poisonous to all low organisms.
Hydrocyanic acid is a general protoplasmic poison, all the lower organisms being very susceptible to its action, while in the higher animals it speedily depresses or paralyses all forms of nerve tissue.
In the first place, the adaptation may be merely subjective, when the empirical condition for the exercise of judgment is furnished by the feeling of pleasure or pain; such adaptation is aesthetic. In the second place, the adaptation may be objective or logical, when empirical facts are given of such a kind that their possibility can be conceived only through the notion of the end realized in them; such adaptation is teleological, and the empirical facts in question are organisms.
They were beneficial organisms and were allowing pathogens to thrive.
It is not feasible to monitor such a range of organisms.
As already described, ocean acidity may increase as phytoplankton (and increased marine organisms) decompose.
adaptations of organisms, Food webs, Energy flow, Coastal management.
Pharyngitis: acute pharyngitis is caused by a variety of organisms including the adenoviruses and Streptococcus pyogenes.
Other common causative organisms include other Gram-negative aerobes, Streptococcus spp. and anaerobes.
amylase enzymes are produced by other organisms, including fungi and bacteria, which carry out external digestion.
Some species have skin appendages that make them resemble kelp, or carry encrusting organisms that make them resemble coral or rocks.
aquatic organisms are included below.
And you would like me to address the fact that " we already have artificial intelligence [and] mechanical organisms " .
autotrophic organisms, this type of predation is called grazing.
biocidal activity with efficacy with efficacy against spores, bacterial, fungal and viral organisms.
Paint manufacturers may use biocides in their products in order to prevent these organisms developing.
These species are widely used model organisms in developmental biology.
biology of organisms, organs, systems, tissues and cells.
All living organisms are classified according to a system which was originally developed around 1753 by a Swedish botanist called Carl von LinnÃ© .
broad-spectrum disinfectant active against viruses, bacteria, fungi and other pathogen organisms (Virkon® S ).
Bell animalcules are tiny unicellular organisms that belong to a group called the ciliates.
clawed frog, one of the model organisms used to study vertebrate development.
The daily rhythm of life is maintained by a circadian clock in organisms ranging from bacteria to humans.
commensal organisms whose presence is essential to our health.
This likewise necessarily occurs with closely allied organisms, which inhabit distinct continents or islands.
cranberry extract treats help prevent micro organisms from attaching to the urinary tract which, in turn, helps prevents infection.
crystallites formed during these processes often have a unique chemistry and morphology as a result of the controls imposed by the organisms.
Specific organisms currently being analyzed in addition to the marine cyanobacteria include the eukaryotic phytoplankton Emiliania huxleyi and Phaeocystis sp.
cytochrome p450 enzymes are present in all organisms from bacteria to humans.
Use a broad-spectrum disinfectant active against viruses, bacteria, fungi and other pathogen organisms (Virkon® S ).
Eventually, the dead, rotting material playing host to this variety of organisms, will totally disintegrate.
duster worms and many other organisms.
In partially edentulous patients, periodontal pockets may act as reservoirs for pathogenic organisms.
engineered organisms are there forever.
Lipid compound A substance containing esters or fatty acids, which are important structural materials in living organisms.
These are tiny organisms, too small to see with the naked eye, that sometimes cause illness in humans.
faeces cat feces - may contain disease organisms.
food poisoning organisms won't grow if they are colder than 5°C.
Invasive organisms, pests and diseases threaten food and agricultural systems and critical terrestrial, freshwater and marine ecosystems and environmental services.
Xenopus laevis - scientific name for the African clawed frog, one of the model organisms used to study vertebrate development.
genomes of higher organisms.
There's been a lot of hype over decoding the genome of humans and other organisms.
Histoplasma duboisii Vanbreuseghem) The spores of these organisms can cause the lung disease histoplasmosis if inhaled (Roberts et al.
Hume: Again, Hovind feigns incredulity that complex systems can evolve, ignoring the point that systems are parts of organisms.
The pH and high oxygen content of the healthy small intestine do not support growth of the organisms.
Data is also collected on the spectrum of organisms isolated from cases of fungal keratitis.
lactobacillus rhamnosus can inhibit the growth of pathogenic organisms in the GI tract and inhibit putrefactive toxins.
No organisms were detected by bronchoalveolar lavage and the pulmonary function tests suggested emphysema with air trapping, hyperinflation and markedly reduced diffusion capacity.
These observations accord with the hypothesis that organisms are polyphasic liquid crystals.
manipulation of biological molecules and organisms.
Production loss from udder quarters with subclinical mastitis has been assessed for several different causative organisms and ranged from 10% to 26% .
micro organisms which prefer acid waters.
The process is similar to composting except it is non thermophilic or a cold process utilizing naturally occurring soil dwelling micro organisms.
These ' good ' organisms compete with and dominate the more harmful microbes.
microhabitats for various organisms.
microscopic marine organisms.
initially microscopic organisms feed on the more succulent ingredients in the pile.
model organisms are beloved by researchers investigating developmental biology - the transformation of an organism from a fertilized egg into an adult.
All living organisms consist of cells; spherical aggregates of biological molecules surrounded by a thin membrane.
The organisms penetrate the gut mucosa via Peyer's patches and multiply within intestinal lymph nodes.
multiplication of the few remaining live organisms.
nematode worm was an unknown in the world of model organisms.
This hypothesis is supported by the fact that only organisms that are able to stimulate neutrophils are associated with renal scarring.
The most simple definition is a group of organisms that can breed together to produce fertile offspring.
All sexually reproducing organisms develop from a single fertilized oocyte by cell multiplication and differentiation.
Bacteria Bacteria are tiny, single-celled organisms that live in the body.
Fungi can live on dead or decaying organic matter or parasitically by invading living organisms.
Such drugs rapidly destroy the pool of infecting organisms.
TRAVELLER'S DIARRHEA Precautionary measures can be taken to protect against disease-causing organisms not found at home.
Intact skin provides an effective barrier to invasion by pathogenic organisms - it is an important part of the body's external defense mechanisms.
Initially microscopic organisms feed on the more succulent ingredients in the pile.
This ought to serve you well for any aquatic organisms you might be looking for.
organisms on the planet.
The micro organisms find it very difficult to settle or reproduce.
During this testing, the concentrate was inoculated with 30 known spoilage organisms and bacteria.
Disease comes from exposure to various nasty micro- organisms, and from genetic infirmities.
The research will look at the complex language which single-cell organisms use to control their behavior.
This is because the decomposer organisms are too cold to work quickly.
Etiology of aspiration pneumonia The organisms involved in aspiration pneumonia are generally those colonizing the upper oropharynx and gut.
outnumbered by an invisible force, hosts to millions of micro organisms.
outstrip supportive factors due to removal of organisms from their natural environment.
Such organisms are therefore termed parasites and medical parasitology is the study of protozoa and helminth infections of man.
Research topics include pathogenesis, virulence factors, immune mechanisms, genetic studies and viruses, prokaryotic organisms, and protozoa.
Killing of micro-organisms by macrophages involves phagocytosis of the organism, followed by the production of oxygen radicals which then kill the phagocytosed organisms.
physics of organisms, by Mae-Wan Ho, World Scientific, Singapore 2 nd ed., 1998.
physiology of organisms, Geology and Elementary Maths for Biologists.
dead phytoplankton and other marine organisms act as carbon dioxide vessels, driving this pump as they sink toward the bottom of the ocean.
polyphyletic group of organisms represented in most of the major groups of fungi.
porphyrin biosynthesis pathway are found in different kingdoms of living organisms.
proclaim boldly that organisms cannot possibly arise by chance processes.
Animal experiments have documented the ability of these organisms to cause acute pyelonephritis by the ascending route of infection against urine flow.
pyramids of biomass, which include the total mass of living organisms at each trophic level.
Exceptions such as these, and those described above involving miracidia containing fully developed redia is evidence of the evolutionary past of these organisms.
Other organisms can use fumarate reductase for ATP production by anaerobic respiration.
We must reject the reductionism that gives priority to molecules over cells and cells over organisms and organisms over populations.
Similar adaptations have been made by organisms carrying saxitoxin, ciguatera and others.
scavengecay of this catch attracts scavenging organisms such as crustaceans, many of which can be commercially important species.
artificial seawater is fortified with trace elements beneficial to marine organisms.
sessile organisms have evolved potent chemical defense systems utilizing compounds with novel architecture.
Upper respiratory tract infections caused by organisms sensitive to cefpodoxime, including sinusitis.
subclinical mastitis has been assessed for several different causative organisms and ranged from 10% to 26% .
substratumer two factors probably have the greatest influence on the organisms that inhabit sand and gravel substrata.
Access to abundant sea water, local marine organisms and fish breeding expertise provides a self sufficiency that ensures a reliable and consistent service.
Nearly all molecules synthesized by living organisms are optically active.
In 1999, we were awarded almost £ 500,000 to develop the study of the molecular systematics of marine organisms.
taking of samples cause damage or distress to, or kill, organisms?
taxonomy of this group of organisms, which has changed frequently over the years, appears to be quite complex.
No living thing exists in isolation; each lives within an ecosystem a community of organisms interacting with one another and their environment.
threonine protein kinases that is ubiquitously expressed in eukaryotic organisms.
This food is also ideal for sponges, tunicates, feather duster worms and many other organisms.
These are also very small organisms and strongly resemble the " tadpole " larval stage of the sessile tunicates.
unicellular organisms such as bacteria which have dramatic effects on our lives.
These pollutants have led to decreases in the populations of common whelks in the North Sea and cause DNA breakdown in some marine organisms.
For the nematode worm was an unknown in the world of model organisms.
They are the most numerous organisms in freshwater zooplankton.
The beginning of definite knowledge on the phenomenon of fermentation may be dated from the time of Antony Leeuwenhoek, who in 1680 designed a microscope sufficiently powerful to render yeast cells and bacteria visible; and a description of these organisms, accompanied by diagrams, was sent to the Royal Society of London.
Fermentation, according to Pasteur, was caused by the growth and multiplication of unicellular organisms out of contact with free oxygen, under which circumstance they acquire the power of taking oxygen from chemical compounds in the medium in which they are growing.
To the study of the life-history of the butyric and acetic organisms we owe the terms "anaerobic" and "aerobic."
This discovery was of great importance to the zymo-technical industries, for it showed that bacteria are not the only undesirable organisms which may occur in yeast.
Portions most liable to destruction, those parts between the tide marks, were found perfectly sound, and showed no signs of the ravages of marine organisms. Other valuable timber trees of the eastern portion of the continent are the blackbutt, tallow-wood, spotted gum, red gum, mahogany, and blue gum, eucalyptus; and the turpentine (Syncarpialaurifolia), which has proved to be more resistant to the attacks of teredo than any other timber and is largely used in wharf construction in infested waters.
In spite of the various details of the Judgment Critique (as to beauty; and as to the " internal " or as Hegel subsequently phrased it " immanent " adaptations seen in living organisms) Kant regards as extremely precarious all these hints of a higher view of nature.
Thus, though he looked on species as fixed, being the realization of an unchanging formative principle (c0vis), he seems, as Ueberweg observes, to have inclined to entertain the possibility of a spontaneous generation in the case of the lowest organisms.
It was natural, therefore, that he rejected the idea of a spontaneous generation of organisms (which was just then being advocated by his friend Forster), not only as unsupported by experience but as an inadequate hypothesis.
The prosecution of such inquiries is beginning to make unnecessary much ingenious speculation of a kind that was prominent from r880 to 'goo; much futile effort has been wasted in the endeavour to find on Darwinian principles special " selection-values " for phenomena the universality of which places them outside the possibility of having relations with the particular conditions of particular organisms. On the other hand, many of those who have been specially successful in grouping diverse phenomena under empirical generalizations have erred logically in posing their generalizations against such a vera causa as the preservation of favoured individuals and races.
Consideration of phylogenetic series, especially from the palaeontological side, has led many writers to the conception that there is something of the nature of a growth-force inherent in organisms and tending inevitably towards divergent evolution.
The group has until recent years been regarded as comprising three classes distinguished by well-marked physiological featuresthe Algae (including the Seaweeds) which contain chlorophyll, the Fungi which have no chlorophyll and therefore lead a saprophytic or parasitic mode of life, and the Lichens which are composite organisms consisting of an alga and a fungus living together in a mutual parasitism (symbiosis); Bacteria were regarded as a section of Fungi.
Bacteria (see BACTERIOLOGY) and Cyanophyceae (see ALGAE), which are often grouped together as Schizophyta, are from points of view of both structure and reproduction extremely simple organisms, and stand apart from the remaining groups, which are presumed to have originated directly or indirectly from the Flagellatae, a group of unicellular aquatic organisms combining animal and plant characteristics which may be regarded as the starting-point of unicellular Thallophytes on the one hand and of the Protozoa on the other.
The importance of this provision in the case of aquatic vascular plants of sturdy bulk is even greater than in that of terrestrial organisms, as their environment offers considerable obstacles to the renewal of the air in their interior.
The processes of putrefaction may be alluded to as affording an instance of such a power in the vegetable organisms. At the same time it must be remembered that the secretion of enzymes by Bacteria is of widespread occurrence.
Animals and plants as agents of disease or injury form part of the larger subject of the struggle for existence between living organisms, as is recognized even by those who do not so readily apprehend that diseased conditions in general are always signs of defeat in the struggle for existence between the suffering organism and its environment, living and non-living.
In one sense, the accumulation of humus and peat is a biological factor, as it is related to the work of organisms in the soil; but the occurrence or otherwise of these organisms in the soil is probably related to definite edaphic and climatic conditions.
Some such species are Blechnum boreale, Aira flexuosa, Calluna vulgaris, Vaccinium, Myrlillus, Rubus, Chamaemorus, Empetrum nigrum, Drosera spp. Some, at least, of these species possess mycorhiza in their roots, and are perhaps unable to live in soils where such organisms are absent.
Within it or its modifications all the vital phen.omena of which living organisms are capable have their origin.
many motile unicellular Algae and swarm spores is also probably concerned with the active response to light exhibited by these organisms. In Euglena viridis, which has been most carefully studied in this respect, the flagellum which brings about the movement bears near its base a minute spherical or oval refractive granule or swelling which is located just in the hollow of the red pigment-spot (fig.