Summary

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.