VJ PREFACE 



University of Michigan, and has based his presentation not alone 

 upon his own experiences, but has profited by the experiences of 

 other instructors with whom he worked. 



No originality is claimed for this textbook. The material 

 contained in it has been collected from many sources, and an 

 attempt has been made to incorporate the results of the latest 

 investigations. The majority of the figures have been borrowed 

 from other textbooks and from original articles in scientific 

 periodicals. The author is indebted to the Macmillan Com- 

 pany for the majority of these illustrations. He wishes also, 

 to thank the following for the use of certain figures : Henry 

 Holt and Co., 149-156; New Era Printing Co., 26, 62, 63; 

 A. I. Root Co., 131, 147; Science Press, 91, 109, no, in, 116; 

 United States Department of Agriculture, 135, 137, 141, 

 142; Wistar Institute of Anatomy and Biology, 12, 13, 25, 

 94. In every case the author's name follows the legend under 

 the figures. Figures i, 2, 3, 31, 49-51, 54, 123, and 157 were 

 drawn by Mr. George M. Curtis under the author's direction. 



The sources of information could not well be acknowledged 

 directly, so the titles of the most important and easily accessible 

 books and original articles have been arranged at the end of the 

 book under the headings of the various chapters. The titles 

 are numbered and are referred to by number in many places in 

 the text. It is hoped that this list will be helpful to teachers, 

 and that students may be encouraged to supplement their own 

 observations and discoveries by consulting the original papers 

 dealing with the topics under discussion. 



In a first course in Zoology, students encounter a large 

 number of scientific terms which cause them more or less 

 confusion. For this reason a glossary has been included. 

 It gives the meaning of the most important terms used, a 

 key to their pronunciation, and shows their derivation. 



In making acknowledgments it is necessary to explain that 

 the present author planned the book with Dr. A. S. Pearse, and 

 that the latter was to have prepared half of the manuscript 



