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OriginOfSpecies - 475 Rows
Column Type #Values Column Stats
id int(11) 475 Column Stats
subject varchar(80) 14 Column Stats
title varchar(250) 139 Column Stats
ordinal int(11) 30 Column Stats
description text 474 Column Stats

475 rows, page 57 of 119 (4/p)
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Export to Excel select * from OriginOfSpecies order by subject, title, ordinal limit 224, 4 (Page 57: Row)
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ordinal
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05 - Laws of Variation 05-03 - Acclimatisation 40 On the whole, we may conclude that habit, or use and disuse, have, in some cases, played a considerable part in the modification of the constitution and structure; but that the effects have often been largely combined with, and sometimes overmastered by the natural selection of innate variations.
05 - Laws of Variation 05-04 - Correlation of Growth 10 I mean by this expression that the whole organisation is so tied together during its growth and development, that when slight variations in any one part occur, and are accumulated through natural selection, other parts become modified.

This is a very important subject, most imperfectly understood, and no doubt wholly different classes of facts may be here easily confounded together.

We shall presently see that simple inheritance often gives the false appearance of correlation.

One of the most obvious real cases is, that variations of structure arising in the young or larvae naturally tend to affect the structure of the mature animal.

larva
larva


The several parts of the body which are homologous, and which, at an early embryonic period, are identical in structure, and which are necessarily exposed to similar conditions, seem eminently liable to vary in a like manner: we see this in the right and left sides of the body varying in the same manner; in the front and hind legs, and even in the jaws and limbs, varying together, for the lower jaw is believed by some anatomists to be homologous with the limbs.
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These tendencies, I do not doubt, may be mastered more or less completely by natural selection; thus a family of stags once existed with an antler only on one side; and if this had been of any great use to the breed, it might probably have been rendered permanent by selection.
05 - Laws of Variation 05-04 - Correlation of Growth 20 Homologous parts, as has been remarked by some authors, tend to cohere; this is often seen in monstrous plants: and nothing is more common than the union of homologous parts in normal structures, as in the union of the petals into a tube.

petal
petal


Hard parts seem to affect the form of adjoining soft parts; it is believed by some authors that with birds the diversity in the shape of the pelvis causes the remarkable diversity in the shape of their kidneys.

bird
bird

pelvis
pelvis

kidney
kidney


Others believe that the shape of the pelvis in the human mother influences by pressure the shape of the head of the child.

In snakes, according to Schlegel, the form of the body and the manner of swallowing determine the position and form of several of the most important viscera.
snake
snake

Hermann Schlegel
Hermann Schlegel
05 - Laws of Variation 05-04 - Correlation of Growth 30 The nature of the bond is frequently quite obscure. Isidore Geoffroy St-Hilaire has forcibly remarked that certain malconformations frequently, and that others rarely, co-exist, without our being able assign any reason.

What can be more singular than the relation in cats between complete whiteness and blue eyes with deafness, or between the tortoise-shell colour and the female sex; or in pigeons between their feathered feet and skin betwixt the outer toes, or between the presence of more or less down on the young pigeon when first hatched, with the future colour of its plumage; or, again, the relation between the hair and teeth in the naked Turkish dog, though here no doubt homology comes into play?

tortoise
tortoise

pigeon
pigeon


With respect to this latter case of correlation, I think it can hardly be accidental, that the two orders of mammals which are most abnormal in their dermal covering, viz., Cetacea (whales) and Edentata (armadilloes, scaly ant-eaters, &c.,) are likewise on the whole the most abnormal in their teeth; but there are so many exceptions to this rule, as Mr. Mivart has remarked, that it has little value.

whale
whale

armadillo
armadillo

anteater
anteater