Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 4, 2025
Gärtner further admits that hybrids between very closely allied species are more variable than those from very distinct species; and this shows that the difference in the degree of variability graduates away.
For in this case the variability will seldom as yet have been fixed by the continued selection of the individuals varying in the required manner and degree, and by the continued rejection of those tending to revert to a former and less modified condition. The principle included in these remarks may be extended. It is notorious that specific characters are more variable than generic.
Genera which are polymorphic in one country seem to be, with a few exceptions, polymorphic in other countries, and likewise, judging from Brachiopod shells, at former periods of time. These facts are very perplexing, for they seem to show that this kind of variability is independent of the conditions of life.
Thereby he is only beating a dead horse, for no such argument is nowadays put forward. The variability of the gold standard of value is acknowledged, whenever a fluctuation in the general level of commodity prices is recorded.
Tail, rudimentary, occurrence of, in man; convoluted body in the extremity of the; absence of, in man and the higher apes; variability of, in species of Macacus and in baboons; presence of, in the early progenitors of man; length of, in pheasants; difference of length of the, in the two sexes of birds. Tait, Lawson, on the effects of natural selection on civilised nations.
Variability of body and mind in man Inheritance Causes of variability Laws of variation the same in man as in the lower animals Direct action of the conditions of life Effects of the increased use and disuse of parts Arrested development Reversion Correlated variation Rate of increase Checks to increase Natural selection Man the most dominant animal in the world Importance of his corporeal structure The causes which have led to his becoming erect Consequent changes of structure Decrease in size of the canine teeth Increased size and altered shape of the skull Nakedness Absence of a tail Defenceless condition of man.
The vesper sparrow, on the other hand, shows a much lower degree of variability, the individuals rarely differing in their songs, while all the nests I have ever found of this sparrow were in open grassy fields upon the ground.
No reversion accompanies mutation, and this fact is perhaps the completest contrast in which these two great types of variability are opposed to each other. The offspring of my mutants are, of course, subject to the general laws of fluctuating variability. They vary, however, around their own mean, and this mean is simply the type of the new elementary species.
This is partly due to differences in exposure, but mainly to alterations of the sensibility of the organs themselves. It is difficult to gain a clear conception of the contrast between individual and partial variability, and neither is it easy to appreciate their cooperation rightly. Perhaps the best way is to consider their activity as a gradual narrowing of possibilities.
He alone is vital in the social scheme who lets nothing in him atrophy and who persists in being varied from all others in the scale of character to the degree of variability that was his at the beginning. I read in your letter nothing but a decision to stop short and give over, as if you had strength for no more than your book and your theory!
Word Of The Day
Others Looking