X PREFACE TO THE FIRST EDITION 



quite usable with older students who are beginning the subject. The 

 nature of the course of which this laboratory work forms a part and 

 the authors' purpose in introducing a much greater number of illustra- 

 tions than is common in laboratory manuals are set forth under the 

 "Remarks to Instructors" which follow this Preface. 



It is impossible to acknowledge the services of all who have con- 

 tributed to the several revisions and thus to the present work. The 

 authors' colleague, Dr. G. W. Tannreuther, and particularly Dr. G. S. 

 Dodds, formerly of the University of Missouri, have been especially 

 helpful. The late Dr. George Lefevre, although not participating 

 actively in any of the revisions, was always keenly interested in the 

 success of the laboratory work' Among many other assistants, E. A. 

 Martin, F. L. Hisaw, E. E. Nelson, F. 0. Coe, Hope Hibbard, Harriet 

 Johnston, and Agnes Orbison have made valuable suggestions in 

 present and past editions. The acknowledgments of figures and other 

 matter taken directly from other authors appear in connection with 

 each item throughout the volume. The authors desire to thank the 

 publishers and others concerned for all such courtesies. To Mr. George 

 T. Kline, biological artist of the University of Missouri, the authors 

 are indebted for his careful work in preparing most of the illustrations 

 from preliminary drafts and selections made by themselves. C. E. 

 Wilson and Wiley Crawford, students at the University of Missouri, 

 have drawn the figures on pages 72 and 77 from nature and other 

 sources. 



University of Missouri 

 Columbia, Missouri 

 November 10, 1924 



