Chance plays a much larger part in the lives of some animals than of others. The frog and the toad lay hundreds of eggs, the fishes spawn thousands, but most birds lay only five or six eggs.
A spendthrift with one hand, Nature is often a miser with the other. She lets loose an army of worms upon the forests, and then sends an ichneumon-fly to check them. She wastes no perfume or color upon the flowers which depend upon the wind to scatter their pollen. Cross-fertilization is dear to her, and she invents many ingenious ways to bring it about, as in certain orchids. She will rob the bones of the fowl of their lime to perfect the shell of the egg. She wastes no wit or cunning on the porcupine or on the skunk, because she has already endowed each of them with a perfect means of defense.
Two things Nature is not chary of--fear and pain. She heaps the measure here because fear puts her creatures on the safe side; it saves them from many real dangers. What dangers have lurked for man and for most wild things in the dark! How silly seems the fear of the horse! a fluttering piece of paper may throw him in a panic. Pain, too, safeguards us; it shields us against real dangers. The pains of childbirth are probably no check upon offspring, because the ecstasy of procreation, especially on the part of the male, overcomes all other considerations.
Mosquitoes for the North and mainly fleas and ticks for the South--this seems to be Nature's decree, at least in this country. The mosquitoes of the Far North pounce upon one suddenly and ferociously, while our Jersey mosquitoes hesitate and parley and make exasperating feints and passes. On the tundra of Alaska, if I stopped for a moment a swarm of these insects rose out of the grass as if they had been waiting for me all the years (as they had) and were so hungry that they could not stand upon the order of their proceeding, but came headlong.
In Jamaica the dogs were persecuted almost to death by the fleas. They were the most sorry, forlorn, and emaciated dogs I ever saw. Life was evidently a burden to them. I remember that Lewis and Clark, in their journey across the continent, were greatly pestered by fleas. I have found that our woodchucks, when they "hole up" in the fall, are full of fleas.