PREFACE 



This book has been rewritten to make certain additions that 

 the experience of teachers has indicated would be useful 

 and to introduce some of the newer topics of general bionomic 

 or ecological importance whose study has marked the past 

 decade. Zoology is a rapidly growing science, and text-books 

 for secondary schools, no less than for colleges, must fre- 

 quently be rewritten to give a proper view of the subject. 



The additions relating to anatomy are intended to round 

 out the student's knowledge as gained from a first-hand dis- 

 section of certain type-forms. What these forms should be 

 is left to the teacher, but they are suggested in the treatment 

 of each chapter dealing with "anatomy and physiology." 

 Some work in dissection of tj'pes is luidoubtedly beneficial, 

 but the danger must be avoided of making the course primarily 

 anatomical. There is this great importance of anatomical 

 study — properly made by the student — that it gives him 

 an understanding of the internal mechanism of organisms, 

 including himself. In the modern development of medicine, 

 which is undertaking more and more to educate the general 

 public so that it may avoid disease, a knowledge on the part 

 of every child of the organs and functions of the body will 

 be of the greatest value. Indeed, it is hardly too much to 

 predict that some day the importance of the dissection by 

 every high-school child of a series of tyjjes leading to the 

 mammal shall be regarded as essential for carrying out the 



V 



