| → is due, as I believe, 1859 1860 1861 1866 |
| seems to be partly due 1869 1872 |
|
| → having 1859 1860 1861 1866 1869 |
| including of course the reproductive systems, having 1872 |
|
|
resist great changes of conditions with unimpaired fertility; and certain species in a group will produce unusually fertile hybrids. No one can tell, till he tries, whether any particular animal will breed under
or any
seed freely under culture; nor can he
till he tries, whether any two species of a genus will produce more or less sterile hybrids. Lastly, when organic beings are placed during several generations under conditions not natural to them, they are extremely liable to vary, which
→is due, as I believe,
to their reproductive systems having been specially affected, though in a lesser degree than when sterility ensues. So it is with hybrids, for
in successive generations are eminently liable to vary, as every experimentalist has observed. |
|
| Thus we see that when organic beings are placed under new and unnatural conditions, and when hybrids are produced by the unnatural crossing of two species, the reproductive system, independently of the general state of health, is affected
in a very similar manner. In the one case, the conditions of life have been disturbed, though often in so slight a degree as to be inappreciable by us; in the other case, or that of hybrids, the external conditions have remained the same, but the organisation has been disturbed by two
structures and
→having
been blended into one. For it is scarcely possible that two organisations should be compounded into one, without some disturbance occurring in the development, or periodical action, or mutual
of the different parts and organs one to
or to the conditions of life. When hybrids are able to breed
inter
they transmit to their offspring from generation to generation the same
organisation, and hence we need not be surprised that their sterility, though in some degree
|
