822 THE AMERICAN JOURNAL OF SOCIOLOGY
logical principles of selection and inheritance. They are more or less automatic in their performances and they are subject to the laws of physical heredity. And it is evident that such modes of action, while gregarious in external appearance and result, as involving two or more individuals in a joint action, are not in any true sense social.
I may cite an instance that falls under my notice as I write. A family of swans on Lake Geneva swim across the lake always in a certain order: one of the parents goes first, the little ones follow next, and the other old one brings up the rear. This is evidently instinctive. The order in which they go is useful for the protection of the young, which are defended by the parents both before and behind. The whole family is involved ; the action is not learned from experience; it is probably not capable of much change or improvement. So considered,^ it is an affair of selected adaptation, knit into the nervous structure, and lacking in special psychological features. Nature shows a wide range of instances similar to this.
If we apply the term solidarity to this mode of association, we should characterize it as "biological" in distinction from other forms. It is innate, unintelligent, unpro gressive ; but deep-seated and very powerful.
2. The Spontaneous or Plastic Group. Comparative psy- chologists find among the animals another form of association also; a group which does not present the features just pointed out as characteristic of that which is purely or largely biological. Animal life is full of collective actions which are due to experi- ence, habits of common or joint action which are not inherited, hut learned. It is in connection with the theory of such actions that the extreme value, in the economy of the animals' conduct, of the impulses of play, imitation, rivalry, etc., is to be recognized. By the exercise of such gregarious or quasi-social impulses as these, the young are trained in the habits of life of their kind.
But the operation of learning, or profiting by experience, by means of such impulses, involves processes of psychology; they
• That is considered as instinctive. I may be mistaken in so considering this particular case.
