A bacterial infection when analysed is seen to be of the nature of an intoxication.
Kruse and C. Nicolle have found that if a bacterial culture be filtered germ-free, an agglutinating serum still produces some change in it, so that particles suspended in it become gathered into clumps.
It has been proved that the pyo-genic bacterial toxins, if not too concentrated, will attract the polymorpho-nuclear leucocytes, but if concentrated, may have a repelling influence.
Not confined to the liquid of granulations; normal blood-serum possesses it to a certain extent, and under bacterial influence it may become very much exalted.
135; Lowit, " Relationship of Leucocytes to Bacterial Action," Beitr.
In the subject of diseases of the skin much has been done, in the minuter observation of their forms, in the description of forms previously unrecognized, and in respect of bacterial and other causation and of treatment.
When these processes continue for a long time in deep water shut off from free circulation so that it does not become aerated by contact with the atmosphere the water becomes unfit to support the life of fishes, and when the accumulation of putrefying organic matter gives rise to sulphuretted hydrogen as in the Black Sea below 125 fathoms, life, other than bacterial, is impossible.
P. 865), the agents of the transformation of cellulose into peaty substances are saprophytic fungi and bacterial ferments.
The ultimate term of bacterial activity seems to be the production of ulmic acid, containing carbon 65.31 and hydrogen 3.85%, which is a powerful antiseptic. By the progressive elimination of oxygen and hydrogen, partly as water and partly as carbon dioxide and marsh gas, the ratios of carbon to oxygen and hydrogen in the rendered product increase in the following manner: The resulting product is a brown pasty or gelatinous substance which binds the more resisting parts of the plants into a compact mass.
Recent work has shown it is too feeble to be relied upon alone, but where really efficient antiseptics, such as mercuric chloride and iodide, and carbolic acid, have been already employed, boracic acid (which, unlike these, is non-poisonous and non-irritant) may legitimately be used to maintain the aseptic or non-bacterial condition which they have obtained.
The melancholy incident illustrates several points of interest: (1) the correctness of the bacterial theory of causation, and the identity of the bacillus pestis as the cause; (2) the infectious character of the pneumonic type of disease; (3) its high fatality; (4) the difficulty of diagnosis.
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.
Wines which have received a check of this description during the main fermentation are very liable to bacterial troubles and frets.
The former also looks on the ordinary disjointing bacterial cell as an oidium, and it must be admitted that since Brefeld's discovery of the frequency of minute oidia and chlamydospores among the fungi, the probability that some so-called bacteria - and this applies especially to the branching forms accepted by some bacteriologists - are merely reduced fungi is increased.
W.) The substance of the bacterial cell when suitably prepared and stained shows in the larger forms a mass of homogeneous protoplasm containing irregular spaces, the vacuoles, which enclose a watery fluid.
The fact that every bacterial cell in a species in most cases appears equally capable of performing all the physiological functions of the species has led most authorities, however, to regard it as the individual - a view which cannot be consistent in those cases where a simple or branched filamentous series exhibits differences between free apex and fixed base and so forth.
In 1892, however, Thaxter rediscovered it and showed its bacterial nature, founding for it and some allied forms the group Myxobacteriaceae.
Apart from numerous fermentation processes such as rotting, the soaking of skins for tanning, the preparation of indigo and of tobacco, hay, ensilage, &c., in all of which bacterial fermentations are concerned, attention may be especially directed to the following evidence of the supreme importance of Schizomycetes in agriculture and daily life.
In addition to the bacterial actions which result in the oxidization of ammonia to nitrous acid, and of the latter to nitric acid, the reversal of such processes is also brought about by numerous bacteria in the soil, rivers, &c. Warington showed some time ago that many species are able to reduce nitrates to nitrites, and such reduction is now known to occur very widely in nature.
The ammonia may be oxidized to nitrites and nitrates, and then pass into the higher plants and be worked up into proteids, and so be handed on to animals, eventually to be broken down by bacterial action again to ammonia; or the nitrates may be degraded to nitrites and even to free nitrogen or ammonia, which escapes.
The nitrogen of the air is absorbed by the nodules, being built up into the bacterial cell and later handed on to the host plant.
Ization of these bacteria to the leguminous plants has always been a very striking fact, for similar bacterial nodules are known only in two or three cases out _ side this particular /01 group. However, Pro fessor Bottomley an nounced at the meeting of the British Association for the Advancement of Science in 1907 that he had succeeded in breaking down this specialization and by a suitable treatment had caused bacteria from leguminous nodules to infect other plants such as cereals, tomato, rose, with a marked effect on their growth.
Beyerinck and Jegunow have shown that some partially anaerobic sulphur bacteria can only exist in strata at a certain depth below the level of quiet waters where SH 2 is being set free below by the bacterial decompositions of vegetable mud and rises to meet the atmospheric oxygen coming down from above, and that this zone of physiological activity rises and falls with the variations of partial pressure of the gases due to the rate of evolution of the SH 2.
W, bacterial tissue.
(After Woromv.) c, cell from bacterial tissues showing nucleus and protoplasm filled with bacteria.
Janthinus, &c., the redpurple of the sulphur bacteria, and indeed most bacterial pigments, solution in water does not occur, though alcohol extracts the colour readily.
The Japanese have cheeses resulting from the bacterial fermentation of boiled Soja beans.
Even when the light is not sufficiently intense, or the exposure is too short to kill the spores, the experiments show that attenuation of virulence, That bacterial fermentations are accompanied by the evolution of heat is an old experience; but the discovery that the " spontaneous " combustion of sterilized cotton-waste does not occur simply if moist and freely exposed to oxygen, philous bacteria.
Bacterial diseases in the higher plants have been described, but the subject requires careful treatment, since several points suggest doubts as to the organism described being the of the disease referred to their agency.
Recently it was urged that the acid contents of plants explained their immunity from bacterial diseases, but it is now known that many bacteria can flourish in acid media.
On the other hand a long list of plant-diseases has been of late years attributed to bacterial action.
Saprophytic bacteria can readily make their way down the dead hypha of an invading fungus, or into the punctures made by insects, and Aphides have been credited with the bacterial infection of carnations, though more recent researches by Woods go to show the correctness of his conclusion that Aphides alone are responsible for the carnation disease.
W.) having given up the specializations of func tion impressed on them during evolution and simply carrying out the fundamental functions of nutrition, growth, and multiplication which mark the generalized activities of the bacterial cell, and at the same time rendered as accessible to the environment by isolation and consequent extension of surface, we should doubtless find them exerting changes in the fermentable fluids necessary to their life similar to those exerted by an equal mass of bacteria, and that in proportion to their approximation in size to the latter.
(1) the methods employed in the study; (2) the modes of action of bacteria and the effects produced by them; and (3) the facts and theories with regard to immunity against bacterial disease.
Pfeiffer (1894), and various anti-bacterial sera have been introduced.
The agglutinative action of the serum of a patient suffering from a bacterial disease, first described in the case of typhoid fever independently by Widal and by Griinbaum in 1896, though led up to by the work of Pfeiffer, Gruber and Durham and others.
In these latter the basic aniline dyes in solution are almost exclusively used, on account of their special affinity for the bacterial protoplasm.
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.
For most purposes the solid media are to be preferred, since bacterial growth appears as a discrete mass and accidental contamination can be readily recognized.
Of course, in applying the method means must be adopted for suitably diluting the bacterial mixture.
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.
The extreme instance of bacterial invasion is found in some of the septicaemias in the lower animals, e.g.
In addition, however, there occur in bacterial diseases symptoms to which the correlated structural changes have not yet been demonstrated.
It has been experimentally shown that conditions such as fatigue, starvation, exposure to cold, &c., lower the general resisting powers and increase the susceptibility to bacterial infection.
This is chiefly to be regarded as an adaptation to surroundings, though the fact that the less virulent members of the bacterial species will be liable to be killed off also plays a part.;,Conversely, the virulence tends to diminish on cultivation on artificial media outside the body, especially in circumstances little favourable to growth.
So far as bacterial immunity is concerned, the anti-serum exerts its action either on the toxin or on the bacterium itself; that is, its action is either antitoxic or anti-bacterial.
The laws of antitoxin production and action are not confined to bacterial toxins, but apply also to other vegetable and animal toxins, resembling them in constitution, viz.
In preparing anti-bacterial sera the lines of procedure correspond to those followed in the case of antitoxins, but the bacteria themselves in the living or dead condition or their maceration products are always used in the injections.
These circumstances serve, in part at least, to explain the fact that the success attending the use of anti-bacterial sera has been much inferior to that in the case of antitoxic sera.
Another property which may be possessed by an anti-bacterial serum is that of agglutination.
Avri, against, and vrJIrrucos, putrefactive), the name given to substances which are used for the prevention of bacterial development in animal or vegetable matter.
Mould and bacterial growths, and causing the appearance, on the surface of their " mushroom garden," of numerous small white bodies formed by swollen ends of the fungus hyphae.
Over and above the bacterial intoxications we have a very extreme degree of fatty degeneration, widely distributed throughout the tissues, which is produced by certain organic and inorganic poisons; it is seen especially in phosphorus and chloroform poisoning.
The bacterial cell is always clothed by a definite cell-membrane, as was shown by the plasmolysing experiments of Fischer and others.
At this temperature the bacterial bodies are extremely brittle, and are thus readily broken up. The study of the nature of toxins requires, of course, the various methods of organic chemistry.
The work on this subject is highly suggestive, and opens up new possibilities with regard to the investigation of bacterial action within the body.
Not only are the general symptoms of poisoning in bacterial disease due to toxic substances, but also the tissue changes, many of them of inflammatory nature, in the neighbourhood of the bacteria.
Though an enormous of amount of work has been done on the subject, no important bacterial toxin has as yet been obtained in a pure condition, and, though many of them are probably of proteid nature, even this cannot be asserted with absolute certainty.
According to this view, then, a part at least of the directly toxic substance is produced in the living body by enzymes present in the so-called toxin obtained from the bacterial culture.
The damping off of seedlingsand in saturated soils not only are the roots and root-hairs killed by asphyxiation, but the whole course of soil fermentation is altered, and it takes time to sweeten such by draining, because not only must the noxious bodies be gradually washed out and the lost salts restored, but the balance of suitable bacterial and fungal life must be restored.
It would appear that there is little prospect of the eradication of this bacterial disorder.
Pathological chemistry has been remarkable chiefly for the knowledge we have obtained of the nature of bacterial poisons.
This disease is probably bacterial in origin.