the more uniformly successful would the mating of all the individuals in a given district tend to become. But all of this renders an interval of sexual inactivity unavoidable; an interval which must constitute a danger unless there were something in the external environment to prevent the male and female from drifting apart. Inasmuch, then, as the occupation of a territory serves to remove all possibility of permanent separation. I suggest that its evolution has afforded the condition under which this beneficial procedure has developed—free to mate when they will, free to seek food where they will, free to pursue their normal routine of existence, and to meet all exigencies as they arise in their ordinary daily life—whilst free to do this, their future, as a pair, is nevertheless secure.
Thus far we have considered the territory in its relation to the discharge of the sexual function. In many of the lower forms of life, the success or the failure of reproduction, so far as the individual is concerned, may be said to end with the completion of the sexual act—the female has but to deposit her eggs in a suitable environment and then her work is done, because in due course and under normal conditions of temperature the young hatch out, and from the first are able to fend for themselves. And so, when we come to consider the question of reproduction in the higher forms of life, we are apt to focus attention too much upon the sexual function and too little upon the con-
