We have spoken of the absence of structural differentiation in the sense organs.
We have nothing structural which corresponds to the former of these.
There is much to be said in favour of the view entertained by some entomologists that the structural and developmental characteristics of may-flies are sufficiently peculiar to warrant the formation for them of a special order of insects, for which the names Agnatha, Plectoptera and Ephemeroptera have been proposed.
Whilst the chances are in favour of some one homoplastic coincidence or structural agreement occurring between some member or other of a large group a and some member or other of a large group b, the matter is very different 2 a o FIG.
The simplicity and smallness of the Mithraic temples are to be accounted for by structural and financial reasons; an underground temple was difficult to construct on a large scale, and the worshippers of Mithras were usually from the humbler classes.
The following structural formulae are assigned to these compounds: R CAN OH R.CCN(OK) > O R C N02K NO 2 N(:O) NO nitrolic acid; erythro-salt; leuco-salt.
Lamarck had put forward the hypothesis that structural alterations acquired by (that is to say, superimposed upon) a parent in the course of its life are transmitted to the offspring, and that, as these structural alterations are acquired by an animal or plant in consequence of the direct action of the environment, the offspring inheriting them would as a consequence not unfrequently start with a greater fitness for those conditions than its parents started with.
Structural complexity is brought about by the superposition of new variations on preceding ones.
Continued existence implies perpetual adaptation to new conditions, and, as the adjustment becomes more refined, the corresponding structural organization becomes more elaborate.
The geographical distribution of mountains is intimately associated with the great structural lines of the continents of which they form the culminating region.
Lameere's classification is founded on the number of abdominal sterna, the nervuration of the wings, the number of malpighian tubules (whether four or six) and other structural characters.
The other structural characters of the Order may be briefly summarized as: - mouth-parts adapted for piercing and sucking, or for suction alone, and consisting of a proboscis formed of the labium, and enclosing modifications of the other usual parts of the mouth, some of which, however, may be wanting; a thorax fused into a single mass; and legs with five-jointed tarsi.
Certain extremely aberrant Diptera, which, in consequence of the adoption of a parasitic mode of life, have undergone great structural modification, are further remarkable for their peculiar mode of reproduction, on account of which the families composing the group are often termed Pupipara.
The principal structural feature is the broad anticline, its axis running north and south, which has brought up the Carboniferous Limestone; this uplifted region is the southern extremity of the Pennine Range.
Along one line there was a gradual elaboration of the tube until it culminated, so far as structural complexity is concerned, in the so-called trapdoor nests or burrows of various families; along the other line the tubular retreat either retains its primitive simplicity in association with a new structure, the snare or net, or is entirely superseded by the latter.
In addition to these two necessary factors, structural conditions play an important part in determining the accumulation of oil and gas.
Kekule was the forerunner of his celebrated benzene theory in particular, and of the universal application of structural formulae to the representation of the most complex organic compounds equally lucidly as the representation of the simplest salts.
The structural relations of these compounds are here shown: R C0.
Benz-oxazoles and -thiazoles have been prepared, benz-isoxazoles are known as indoxazenes; benzo-pyrazoles occur in two structural forms, named indazoles and isindazoles.
We have now passed in review the principal structural features in which Limulus agrees with Scorpio and differs from other Arthropoda.
Thirdly, those members of a group which, whilst exhibiting undoubted structural characters indicative of their proper assignment to that group, yet are simpler than and inferior in elaboration of their organization to other members of the group, are not necessarily representatives of the earlier and primitive phases in the development of the group - but are very often examples of retrogressive change or degeneration.
Among the city's manufactures are agricultural implements, iron bridges and other structural iron work, watches and watch-cases, steel, engines, safes, locks, cutlery, hardware, wagons, carriages, paving-bricks, furniture, dental and surgical chairs, paint and varnish, clay-working machinery and saw-mill machinery.
In the first hybrid generation formed by the union of the reproductive germs of the positive variety (that possessing the structural character selected for observation) with those of the negative variety, it is not surprising that all or nearly all the individuals were found to exhibit, as a result of the mixture, the positive character.
Oh, and they change color if they detect structural weakness in the material to which they are affixed.
Other important structural features are mentioned below.
For the internal structural details of the micrometer the reader is referred to the article " Micrometer " in the 9th edition of the Encyclopaedia Britannica.
The freeliving differ from the majority of the parasitic forms in undergoing no metamorphosis; they also possess certain structural peculiarities which led Bastian (Trans.
The capacity of camels for travelling long distances without water - owing to special structural modifications in the stomach - is familiar to all.
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.
The term Anatomy, originally employed in biological science to denote a description of the facts of structure revealed on cutting up an organism, whether with or without the aid of lenses for the purposes of magnification, is restricted in the present article, in accordance with a common modern use, to those facts of internal structure not concerned with the constitution of the individual cell, the structural unit of which the plant is composed.
Such a system is called a tissuesystem, the word tissue being employed for any collection of cells with common structural, developmental, or functional characters to which it may be conveniently applied.
In the first place, the continued study of human population has thrown additional light on some of the questions involved, whilst the progress of microscopical research has given us a clear foundation as to the structural facts connected with the origin of the egg-cell and sperm-cell and the process of fertilization.
He selected a variety with some one marked structural feature and crossed it with another variety in which that feature was absent.
The analysis of the specific variations of organic form so as to determine what is really the nature and limitation of a single " character " or " individual variation," and whether two such true and strictly defined single variations of a single structural unit can actually " blend " when one is transmitted by the male parent and the other by the female parent, are matters which have yet to be determined.
There remains for consideration the one important structural difference between the two animals.
This fact renders their association with the Crustacea impossible, if classification is to be the expression of genetic affinity inferred from structural coincidence.
We have now to offer a classification of the Arachnida and to pass in review the larger groups, with a brief statement of their structural characteristics.
He developed an original system of divinity, somewhat on the structural plan of that of Samuel Hopkins, and, in Emmons's own belief, contained in and evolved from Hopkinsianism.
Its railway car repair and construction shops, belonging to the Norfolk & Western railway, employed in that year 66.9% of the total number of factory wage-earners; pig-iron, structural iron, canned goods, bottles, tobacco, planing-mill products and cotton are among the manufactures.
From these structural and palaeontological evidences, geologists suppose that the formation of the cave was carried on simultaneously with the excavation of the valley; that the small streams, flowing down the upper ramifications of the valley, entered the western opening of the cave, and traversing the fissures in the limestone, escaped by the lower openings in the chief valley; and that the rounded pebbles found in the shingle bed were carried in by these streams. It would be only at times of drought that the cave was frequented by animals, a theory which explains the small quantity of animal remains in the shingle.
Every critic could recognize the structural merits of the earlier plays, for their operatic conventionalities and abruptness of motive are always intelligible as stage devices.
Benzo-ortho-diazines exist in two structural forms, cinnolin and phthalazine; benzo-meta-diazines are known as quinazolines; benzo-para-diazines are termed quinoxalines; the dibenzo-compounds are named phenazines, this last group including many valuable dyestuffs - indulines, safranines, &c. In addition to the types of compounds enumerated above we may also notice purin, tropine and the terpenes.