into active co-operation, as among rooks where one of the flock keeps watch while the rest feed, or as among beavers where a number work together in making dams, or as among wolves where, by a plan of attack in which the individuals play different parts, prey is caught which would otherwise not be caught; there is still greater advantage to the individuals and to the species. And, speaking generally, we may say that gregariousness, and cooperation more or less active establish themselves in a species only because they are profitable to it; since, otherwise, survival of the fittest must prevent establishment of them.
But now mark that this profitable association is made possible only by observance of certain conditions. The acts directed to self-sustentation which each performs, are performed more or less in presence of others performing like acts; and there tends to result more or less interference. If the interference is great, it may render the association unprofitable. For the association to be profitable the acts must be restrained to such an extent as to leave a balance of advantage. Survival of the fittest will else exterminate that variety of the species in which association begins.
Here, then, we find a further factor in sub-human justice. Each individual, receiving the benefits and the injuries due to its own nature and consequent conduct, has to carry on that conduct subject to the restriction that it shall not in any large measure impede the conduct by which each other individual achieves benefits or brings on itself injuries. The average conduct must not involve aggressions of such amounts as to cause evils which outbalance the good obtained by co-operation. Thus, to the positive element in sub-human justice has to be added, among gregarious creatures, a negative element.
The necessity for observance of the condition that each member of the group while carrying on the pursuit of self-sustentation and sustentation of offspring, shall not seriously impede the like pursuits of others, makes itself so felt, where association is established, as to mold the species to it. The mischiefs from time to time experienced when the limits are transgressed, continually discipline all in such ways as to produce regard for the limits; so that such regard becomes, in course of time, a natural trait of the species. For, manifestly, regardlessness of the limits, if great and general, causes dissolution of the group. Those varieties only can survive as gregarious varieties in which there is an inherited tendency to maintain the limits.
Yet, further, there arises such general consciousness of the need for maintaining the limits, that punishments are inflicted on transgressors—not only by aggrieved members of the group, but by the group as a whole. A "rogue" elephant (always distin-
