IV PREFACE 



learn only to follow directions, while they should be encouraged 

 to devise their own methods of getting at the facts. For the 

 comparative study of related forms complete directions are 

 not needed and should not be given. The method sometimes 

 used, evidently the favorite method of Agassiz, of giving a 

 student an animal without directions and letting him work out 

 his own salvation, is the true research method, and to this all 

 who continue with Zoology must come in time. It is, of course, 

 laborious and time consuming and not adapted to course work, 

 but there is danger that its great value will be overlooked. 

 It is so much easier for both instructor and student to follow 

 directions. 



The type method of laboratory study has for many years 

 been the prevailing method, but care needs to be exercised to 

 keep students from making everything conform to type, and in 

 leading them to see the wonderful adaptations that fit the dif- 

 ferent animals for their particular lives. The manual is not 

 intended to lead students to a knowledge of comparative 

 anatomy alone, but to an appreciation of adaptation as well. 



There has been no attempt to make the literature list at 

 all complete, but it seems desirable to refer students to some of 

 the available papers, for by consulting them in connection with 

 their laboratory work they become acquainted with methods of 

 work and develop the spirit of research that is the beginning of 

 real understanding. 



Certain books that have not been mentioned under the 

 special heads, as they apply to practically all groups, should 

 be used freely for reference. Among these may be mentioned 

 Parker and Haswell, Text-book of Zoology, Macmillan; Lan- 

 kester, A Treatise on Zoology, Black; Harmer and Shipley, 

 The Cambridge Natural History, Macmillan; Lang, Lehrbuch 

 der Vergleichenden Anatomie, Fischer; or the English transla- 

 tion, Macmillan; Korschel't und Heider, Lehrbuch der Vergleich- 

 enden Entwicklungsgeschichte, Fischer; or the English trans- 

 lation, Macmillan; Delage et Herouard, Traite de Zoologie 

 Concrete, Schmidt; Pratt, A Manual of Common Invertebrate 

 Animals, McClurg & Co. ; MacBride, Text-book of Embryology, 

 Vol. I, Macmillan; Verrill and Smith, Invertebrate Animals 

 of Vineyard Sound, Bui. U. S. F. C., 1871; and Sumner, Osborn ; 



