X PREFACE 



chemical departments of the University. I must especially 

 thank for favors Professor W. C. Sabine, Dr. G. W. 

 CoGGESHALL, and Dr. H. E. Sawyee. Of my zoological 

 associates, I am greatly indebted to Dr. G. H. Parkee, who 

 has read nearly the entire manuscript and has offered valuable 

 criticisms on it, and to Professor E. L. Maek, who has 

 read parts of the manuscript and proof and has made important 

 suggestions and emendations. I am also greatly indebted to 

 Mr. Chaeles Bullaed for his kindness in making photo- 

 graphs of figures from which most of the illustrations of the 

 First Part were reproduced. Finally, I cannot forbear to men- 

 tion the painstaking work of my wife, Geeteudb Ceotty 

 Davenpoet, in preparing the manuscript for the press and 

 revising the proofs. 



As I send out this work I do so with the hope that it may 

 stimulate to even greater activity in the field of experimental 

 morphology. The subject is new, its importance hardly yet 

 generally recognized, its needs incompletely appreciated. In 

 its scope it embraces much of physics and chemistry, for life 

 and development are to be studied as the physicist studies light 

 and heat, or as the chemist studies solutions and combustion. 

 They are phenomena which must be analyzed by the use of 

 instruments of precision to determine the quality and quantity 

 of the acting agents, and to measure the change in the phe- 

 nomena resulting from a change in these agents. No other 

 field offers a better opportunity for the utilization of a broad 

 scientific training. The times, too, are auspicious. Biology 

 has never before attracted so many enthusiastic workers as it 

 does to-day. As Deiesch has said, "Die Lust an thatsach- 

 licher exacter biologischer Forschung ist erwacht"; and the 

 greatest problem of morphology is ever more and more the 

 object of this biological experimentation. 



CHARLES benedict DAVENPORT. 

 Caiibeidge, Mass., Dec. 1, 1896. 



