Introduction

OR some inexplicable reason, the word animal, in common parlance, is restricted to the mammals. As a matter of fact, the bird, the fish, the insect, and the snake have as much right to be called animals as has the squirrel or the deer. And while I believe that much freedom in the matter of scientific nomenclature is permissible in nature-study, I also believe that it is well for the child to have a clearly defined idea of the classes into which the animal kingdom is divided; and I would have him gain this knowledge by noting how one animal differs from another rather than by studying the classification of animals in books. He sees that the fish differs in many ways from the bird and that the toad differs from the snake; and it will be easy for him to grasp the fact that the mammals differ from all other animals in that the young are nourished by milk produced for this purpose in the breasts of the mother; when he understands this, he can comprehend how such diverse forms as the whale, the cow, the bat, and human beings are akin.