by Professor L. E. Eastham Formerly Professor of Zoology in the University of Sheffield Most books are written with the intention of supplying some particular need, but few end with such single purpose. Mrs. Mellanby's is no exception, for while the author planned this work to serve as a guide to the school pupil, which function it fulfils in an admirable way, it will also prove of value to the teacher, the university student and the amateur naturalist. While it may be argued that it is not the function of the Uni versities to teach Natural History in the commonly accepted sense, it will always be the aim of Zoologists to know more about animals, what they are and do, where they live and why they live in particular environments. It is unfortunate, in view of the fact that the majority of students of Zoology enter the teaching pro fession, that the increasing load of instruction in morphology, physiology, cytology, genetics, evolution and the like frequently makes a personal study of animal life in relation to environment almost impossible. The fortunate ones visit the sea for a fort night's course in Marine Ecology; the others take posts in schools without even this respite and set about converting their academic learning to a school curriculum. The result is an undesirable and often slavish imitation of university method in the school class room.