guished as unusually malicious) is one which, has "been expelled from the herd: doubtless because of conduct obnoxious to the rest—probably aggressive. It is said that from a colony of beavers an idler is banished, and thus prevented from profiting by labors in which he does not join: a statement made more credible by the fact that drones, when no longer needed, are killed by worker-bees. The testimonies of observers in different countries show that a flock of crows, after prolonged noise of consultation, will summarily execute an offending member. And an eye-witness affirms that among rooks, a pair which steals the sticks from neighboring nests has its own nest pulled to pieces by the rest.
Here, then, we see that the a priori condition to harmonious co-operation comes to be tacitly recognized as something like a law; and there is a penalty consequent upon breach of it.
That the individual shall experience all the consequences, good and evil, of its own nature and consequent conduct, which is that primary principle of sub-human justice whence results survival of the fittest, is, in creatures that lead solitary lives, a principle complicated only by the responsibilities of parenthood. Among them the purely egoistic actions of self-sustentation have, during the reproductive period, to be qualified by that self-subordination which the rearing of offspring necessitates, but by no other self-subordination. Among gregarious creatures of considerable intelligence, however, the welfare of the species occasionally demands a further self-subordination.
We read of bisons that, during the calving season, the bulls form an encircling guard around the herd of cows and calves, to protect them against wolves and other predatory animals: a proceeding which entails on each bull some danger, but which conduces to the preservation of the species. Out of a herd of elephants about to emerge from a forest to reach a drinking place, one will first appear and look round in search of dangers, and, not discerning any, will then post some others of the herd to act as watchers; after which the main body comes forth and enters the water. Here a certain extra risk is run by the few that the many may be the safer. In a still greater degree we are shown this kind of action by a troop of monkeys, the members of which will combine to defend or rescue one of their number; for though in any particular case the species may not profit, since more mortality may result than would have resulted, yet it profits in the long run by the display of a character which makes attack on its groups dangerous.
Evidently, then, if by such conduct one variety of a gregarious species keeps up, or increases, its numbers, while other varieties, in which self-subordination thus directed does not exist, fail to do
