At least one of the psychological side problems demands especial attention, the mental life of the animals. Animal psychology is no longer made up of hunting stories and queer observations on ants and wasps, and gossip about pet cats and dogs and canary birds. It has become an exact science, which is housed in the psychological laboratories of the universities. And with this change the centre of interest has shifted, too. The mind of the animals is not studied in order to satisfy our zoölogical interest, but really to serve an understanding of the mental functions. It was therefore appropriate to introduce those methods which had been tested in human psychology. In our Harvard Psychological Laboratory, in which a whole floor of the building is devoted exclusively to animal experiments under specialists, single functions like memory or attention or emotion are tested in earthworms or turtles or pigeons or monkeys, and the results are no less accurate than those of subtlest human work. But this experimental animal psychology has so far served theoretical interests only. It stands where human psychology stood before the contact with pedagogy, medicine, law, commerce, and industry suggested particular formulations of the experiments. Such contact with the needs of practical life ought to be secured now for animal psychology. The farmer who has to do with cows and swine and sheep, with dogs and horses, with chickens and geese, with pigeons and bees, ought to have an immediate interest to seek this contact. But his concern ought to go still further. He has to fight the animals that threaten his harvest.