This book is designed to be used quite as much in the laboratory or with specimens in hand, as in the class-room. If Zoology is to be studied as a mental discipline, or even if the student desires simply to get at a genuine knowledge, at first hand, of the structure of the leading types of animal life, he must examine living animals, watch their movements and habits, and finally dissect them, as well as study their mode of growth before and after leaving the egg or the parent, as the case may be. But the young student in a few weeks' study in the laboratory cannot learn all the principles of the science. Hence, he needs a teacher, a guide, or at least a manual of instruction. This work is an expansion of a course of lectures for college students, but has been prepared to suit the wants of the general reader who would obtain some idea of the principles of the science as generally accepted by advanced zoologists, in order that he may understand the philosophical discussions and writings relating to modem doctrines of biology, especially the law of evolution and the relations between animals and their surroundings.
The book has been prepared, so far as possible, on the inductive method. The student is presented first with the facts; is led to a thorough study of a few typical forms, taught to compare these with others, and finally led to the principles or inductions growing out of the facts.