What people are saying - Write a review
We haven't found any reviews in the usual places.
Other editions - View all
acters adduced advance in development Animals and Plants argument arise assumption breeder breeds Cattle cause char close-interbreeding constitutional vigor coordination correlation crystal Darwin says Darwin's theory defects degeneration degree disproportionate development distinct species divergence of character divergent varieties domestication entailed evil effects evil results evolved explain extinction facts fancier fancy fancy breeds favorable flowers Fowl given species Herbert Spencer hypothesis ignorance imply improvements in-and-in individuals innate tendency interbred interbreeding law of nature legs lessened fertility long-lost characters Man's Selection ment modification mongrels Natural Selection normal number of characters occur offspring once lost Origin of Species parents peculiarities peloric perfect type phenomena physiological Pigeon pistils pollen positive characters positive variations proportion proportionate development races re-development regain remarks reproductive element respective species says Darwin seed self-fertilization self-impotent Sheep slight stamens sterility of hybrids structure Struggle for Existence theory of Reversion tion vary viduals wholly
Page 144 - We behold the face of nature bright with gladness, we often see superabundance of food ; we do not see, or we forget, that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life ; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey...
Page 144 - Climate plays an important part in determining the average numbers of a species, and periodical seasons of extreme cold or drought, I believe to be the most effective of all checks.
Page 161 - Can it, then, be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations useful in some way to each being in the great and complex battle of life, should sometimes occur in the course of thousands of generations ? If such do occur, can we doubt (remembering that many more...
Page 143 - Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult — at least I have found it so — than constantly to bear this conclusion in mind.
Page 98 - In every living creature we may feel assured that a host of long-lost characters lie ready to be evolved under proper conditions. How can we make intelligible and connect with other facts, this wonderful and common capacity of reversion, — this power of calling back to life long-lost characters...
Page 315 - In Saxony the importance of the principle of selection in regard to merino sheep is so fully recognised, that men follow it as a trade: the sheep are placed on a table and are studied, like a picture by a connoisseur; this is done three times at intervals of months, and the sheep are each time marked and classed, so that the very best may ultimately be selected for breeding.
Page 186 - Nothing is more indicative of high breeding than this; and the legs should be no longer than, when fully fat, would just prevent the animal's belly from trailing upon the ground. The leg is the least profitable portion of the hog, and we therefore require no more of it than is absolutely necessary for the support of the rest.
Page 54 - I have stated that the most probable hypothesis to account for the reappearance of very ancient characters, is — that there is a tendency in the young of each successive generation to produce the long-lost character, and that this tendency, from unknown causes, sometimes prevails.
Page 67 - Crossing as a direct cause of Reversion. — It has long been notorious that hybrids and mongrels often revert to both or to one of their parent- forms, after an interval of from two to seven or eight, or, according to some authorities, even a greater number of generations. But that the act of crossing in itself gives an impulse towards reversion, as shown by the reappearance of long-lost characters, has never, I believe, been hitherto proved.