VI PREFACE 



medicine, forestry, etc. As is natural, however, the zoolog- 

 ical aspect has been emphasized since it affords indispensable 

 data for the interpretation of Man himself. For courses in 

 general zoology, therefore, the book will be found adequate 

 in its treatment of animals, while chapters VIII and IX on 

 plants may readily be omitted, without breaking the con- 

 tinuity of the discussion. 



The author is indebted, of course, to innumerable sources 

 for the facts and principles outlined. The content has 

 grown by accessions year by year. Nearly all the stand- 

 ard treatises have been drawn upon, but those which 

 have been most generally suggestive are listed in the bibli- 

 ographies of the respective chapters. Specific mention, how- 

 ever, should be made here of Professor Wilder's History of 

 the Human Body, Professor Conklin's Heredity and En- 

 vironment in the Development of Men, Professor Ganong's 

 Text-book of Botany, and Professor Coulter's Evolution of 

 Sex in Plants. 



The author has availed himself of the constructive criticism 

 generously given by Professor B. W. Kunkel of Lafayette 

 College, Professor E. H. Cameron of the University of 

 Illinois, and his colleagues at Yale, Professors R. G. Harrison, 

 W. R. Coe, A. Petrunkevitch, F. P. Underbill, Henry 

 Laurens, G. A. Baitsell, W. W. Swingle, and Dr. J. W. 

 Buchanan, who have read the book either in manuscript or 

 in the mimeographed form in which it has been used by the 

 Yale classes. And Professor Baitsell's interest in the work 

 of the course has made it possible to impose upon him the 

 added task of reading the book at each stage of its develop- 

 ment. Miss Hope Spencer of the Yale Laboratory has as- 

 sumed with enthusiasm a considerable portion of the editorial 

 work involved in seeing the book through the press. 

 Finally, the author's indebtedness to the criticism and 



