This theory is also strengthened by some few other facts in regard to
instincts; as by that common case of closely allied, but distinct, species,
when inhabiting distant parts of the world and living under considerably
different conditions of life, yet often retaining nearly the same
instincts. For instance, we can understand, on the principle of
inheritance, how it is that the thrush of tropical South America lines its
nest with mud, in the same peculiar manner as does our British thrush; how
it is that the Hornbills of Africa and India have the same extraordinary
instinct of plastering up and imprisoning the females in a hole in a tree,
with only a small hole left in the plaster through which the males feed
them and their young when hatched; how it is that the male wrens
(Troglodytes) of North America, build "cock-nests," to roost in, like the
males of our Kitty-wrens,--a habit wholly unlike that of any other known
bird. Finally, it may not be a logical deduction, but to my imagination it
is far more satisfactory to look at such instincts as the young cuckoo
ejecting its foster-brothers, ants making slaves, the larvae of
ichneumonidae feeding within the live bodies of caterpillars, not as
specially endowed or created instincts, but as small consequences of one
general law leading to the advancement of all organic beings--namely,
multiply, vary, let the strongest live and the weakest die.
Pages:
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448