One reason why this cannot be done is because in no case of morphological variation do we really know what these initial stages are.
Hence, in organisms, as in salts, morphological identity may be due to a community of causal connexion, rather than community of descent.
The bodies of almost all organisms have, however, more or less definite forms, which may be all classed under seven morphological categories.
The next morphological category may be spoken of as unipolar symmetry.
Chemical resemblance between groups, as indicating morphological relations, has been well shown.
This complexity of chemical composition of saponin is admirably adapted for the nutrition of the plant, and it is associated with the corresponding complexity of the morphological elements of the plant's organs.
The Thuja occidentalis[39] in the juvenescent and adult form, offers an example wheremorphological and chemical differences go hand in hand.
If some varieties are missing prepare a second stock dish from other colonies on plate 3, and repeat the process until each morphological form or tinctorial variety has been secured in subculture.
The purity of the cultivation; this can only be determined when gross morphological differences exist between the organisms present.
A short consideration of certain morphological facts will therefore be necessary at the start.
The morphological side of the subject is interesting enough to the scientist, but to him alone.
Thus at present the different species are distinguished rather by their physiological than their morphological characters.
Footnote 40: Morphological differences are less in low than in high races, and the less civilized the race, the less is the physical difference of the sexes.
On the other hand, the morphologicaldifferences do not give the two groups an amount of morphological differences that would justify full generic rank for each.
In some instances such centres appear to have an important morphological significance, and in other instances they would seem to be determined by the size of the cartilage about to be ossified.
Before entering into the consideration of the morphological value of the various parts of this cord, it will be convenient to describe the more important features of its ontogeny.
I have avoided using this nomenclature to simplify my description, but it is of the utmost importance that the morphological fact should be grasped.
The morphological significance of the postanal gut and of the neurenteric canal has already been spoken of in Chapter XII.
The termination of the notochord immediately behind the fore-brain is, however, an argument in favour of the morphological distinctness of the latter structure.
But on reflection it will appear that so long as the embryo is simply extended on the yolk-sphere, the point where the ventral surface begins has to be decided on purely morphological grounds.
This commissure has as yet only been found in a complete form in Elasmobranchii; but it is nevertheless to be regarded as a very important morphological structure.
Ichthyopsida and from the similarity of some of its parts to certain organs found amongst the Chaetopoda[197], has a great morphological importance.
Another form of perhaps still greater morphological interest is the larva of Dactylethra.
Most roots occur as several parts of speech, and the determination of whether a root is basically a noun, adjective, or verb depends upon a series of morphological and syntactic criteria the details of which cannot be presented here.
The exception to this rule is forms which contain dead affixes—affixes which are not part of the productive or even live Cebuano morphological (inflectional and derivational) systems.
The entries are liberally illustrated, with the primary aim of clarifying the meaning and with a secondary aim of exemplifying the morphological characteristics of the affixed forms.
It is difficult to estimate the value of abnormalities as evidence bearing on morphological interpretation; the chief danger lies perhaps in attaching undue weight to them, but there is also a risk of minimizing their importance.
Evolution, or development, is, in fact, at present employed in biology as a general name for the history of the steps by which any living being has acquired the morphological and the physiological characters which distinguish it.
Rosenkranz, who in his work Hegel's Naturphilosophie seeks to develop Hegel's idea of an earth-organism in the light of modern science, recognizing in crystallization the morphological element.
The changes, which the individual organism experiences during its life in its material, physiological and morphological organization, are in part transmitted to its progeny.
The presence on plants and animals of any autochthon-morphological characters means death to Darwinism, because these can never be explained by means of selection and struggle for existence.
Eimer is too much inclined towards the other extreme; he does not admit the existence of adaptive-morphological characteristics.
This section deals with the refutation of criticism of the author's interpretations, and endeavors to harmonize the discords that in this, as in all complex morphological research, make progress slow though surer.
The divergence of psychic character which thus arises leads, in the course of generations, to the formation of new instincts, just as the divergence of morphological character gives rise to new species.
However, by the very process of division the individuality of the unicellular creature has been destroyed; both its physiological and its morphological unity have gone.
Among the numerous classes of animals which modern zoology distinguishes the mammals occupy a pre-eminent position, not only on morphological grounds, but also for physiological reasons.
The instincts of species show individual differences, and are just as subject to modification under the law of adaptation as the morphological features of their bodily structure.
For the historical succession of vertebrate fossils corresponds completely with the morphological evolutionary scale which is revealed to us by comparative anatomy and ontogeny.
Upon a derivative theory this morphological conformity is explained by community of descent; and it has not been explained in any other way.
In the absence of distinguishing morphological characteristics we can only conclude that the middorsal stripe is a pattern variant and that Boulenger was correct in synonymizing flavolineatus with taurinus.
The geographical distributions and morphologicalcharacteristics of these four genera suggest that they are more closely related to one another than with any other hylid genera.
As one listened to him one felt that comparative anatomy was indeed worthy of the devotion of a life, and that to solve a morphological problem was as fine a thing as to win a battle.
Which," wrote Lord Farrer, "is just what I wanted as an outline of the Biological and Morphological discussion of the last 100 years.
Thus science has got so far ahead of me that I hesitate to say much about a difficult morphological question--all the more, as old men like myself should be on their guard against over-much tenderness for their own speculations.
The degree of morphological difference between ferox and the forms in southwestern Texas and northern Mexico, suggests that the time of separation antedated the Pleistocene.
On the basis of morphological criteria, I suspect that ater and emoryi are genetically compatible.
Protopodite, endopodite, exopodite, and epipodite were considered to be the morphological units of the crustacean limb.
From a common-sense point of view it is probably of greater importance to realize how variable the distribution of small arteries is than to remember the names of twigs which are of neither surgical nor morphological importance.
Wright, "The Mandible of Man from the Morphological and Anthropological points of view," Essays and Studies presented to W.
Cytological studies on Nyctotherus ovalis with special reference to its morphological types.
Although some of the latter species show very pronounced morphological adaptations to a cave life, many others resemble their noncavernicolous relatives.
Powers, "Morphological Variation and its Causes in Amblystoma tigrinum.
