M Database Inspector (cheetah)
Not logged in. Login


133 rows, page 1 of 34 (4/p)
1 2 3 4 5 6 7 10 20 30 34

Export to Excel select * from OriginOfSpecies where ordinal = '10' order by subject limit 4 (Page 1: Row)
subject Desending Order (top row is first)
title
ordinal
description
01 - Variations Under Domestication 01-02 - Effects of Habit 10 Changed habits produce an inherited effect, as in the period of the flowering of plants when transported from one climate to another. With animals the increased use or disuse of parts has had a more marked influence; thus I find in the domestic duck that the bones of the wing weigh less and the bones of the leg more, in proportion to the whole skeleton, than do the same bones in the wild-duck;
duck
duck


and this change may be safely attributed to the domestic duck flying much less, and walking more, than its wild parents.
01 - Variations Under Domestication 01-04 - Inheritance 10 The results of the various, unknown, or but dimly understood laws of variation are infinitely complex and diversified.

It is well worth while carefully to study the several treatises on some of our old cultivated plants, as on the hyacinth, potato, even the dahlia, &c. and it is really surprising to note the endless points of structure and constitution in which the varieties and sub-varieties differ slightly from each other.
hyacinth
hyacinth

potato
potato

dahlia
dahlia


The whole organisation seems to have become plastic, and departs in a slight degree from that of the parental type.
Full Size

01 - Variations Under Domestication 01-05 -Character of Domestic Varieties 10 When we look to the hereditary varieties or races of our domestic animals and plants, and compare them with closely allied species, we generally perceive in each domestic race, as already remarked, less uniformity of character than in true species.
Full Size Full Size

Domestic races often have a somewhat monstrous character; by which I mean, that, although differing from each other, and from other species of the same genus, in several trifling respects, they often differ in an extreme degree in some one part, both when compared one with another, and more especially when compared with the species under nature to which they are nearest allied. With these exceptions (and with that of the perfect fertility of varieties when crossed,- a subject hereafter to be discussed), domestic races of the same species differ from each other in the same manner as do the closely-allied species of the same genus in a state of nature, but the differences in most cases are less in degree.

This must be admitted as true, for the domestic races of many animals and plants have been ranked by some competent judges as the descendants of aboriginally distinct species, and by other competent judges as mere varieties.
01 - Variations Under Domestication 01-06 - Difficulty of distinguishing between Varieties and Species 10 In attempting to estimate the amount of structural differencebetween allied domestic races, we are soon involved in doubt, from not knowing whether they are descended from one or several parent species.

This point, if it could be cleared up, would be interesting; if, for instance, it could be shown that the greyhound, bloodhound, terrier, spaniel, and bull-dog, which we all know propagate their kind truly, were the offspring of any single species, then such facts would have great weight in making us doubt about the immutability of the many closely allied natural species-

greyhound
greyhound

bloodhound
bloodhound

terrier
terrier

spaniel
spaniel

bulldog
bulldog


for instance, of the many foxes- inhabiting different quarters of the world. I do not believe, as we shall presently see, that the whole amount of difference between the several breeds of the dog has been produced under domestication;

fox
fox


I believe that a small part of the difference is due to their being descended from distinct species.

In the case of strongly marked races of some other domesticated species, there is presumptive or even strong evidence, that all are descended from a single wild stock.