vi PREFACE 



and models, according to the facilities of the laboratory and the 

 ideas of the instructor. 



It is assumed that the instructor has a much broader and more 

 detailed knowledge of the subject than is represented in these 

 outlines. 



The authors wish to acknowledge their indebtedness to Dr. 

 Mary J. Fisher, Dr. A. Grace Mekeel, and the Misses Eleanor C. 

 McMullen and Lillian A. Phelps, who have used these outlines 

 during the building period and have offered valuable suggestions 

 and criticisms. Grateful acknowledgment is also made of the 

 efforts and success of Miss Mary Mekeel in producing the 

 illustrations. 



H. D. R. 

 B. P. Y. 



Ithaca, N. Y. 

 July, 1930. 



