Paleobotany and Zoology. 241 



24. Experimental Zoology ; by Thomas Hunt Morgan. Pp. 

 xii + 454. ' New York 1907 (The Macmillan Company). — During 

 the past decade a considerable proportion of the zoologists in all 

 parts of the world have extended the purely observational and 

 descriptive study of animals to include a consideration of the 

 behavior of the organism under artificial conditions. Such an 

 intense interest has recently been aroused by the results obtained 

 by these studies, that the experimental side of the study of zoology 

 is receiving a rapidly increasing share of the energy of the 

 younger generation of zoologists, as the pages of almost any of 

 our biological journals will attest. Our knowledge of the 

 structure and normal functions of animals has now advanced 

 to the point where it seems profitable to inquire more closely 

 into those factors which naturally operate in the development of 

 the individual and those which have brought about the so-called 

 evolution of the race. The zoologist is no longer content to 

 know of what parts the animal is constructed and the normal 

 function of each of these parts, but he must also ask as to the 

 ultimate causes which have produced the results which he observes. 

 The precise factors which operate in the organic world can per- 

 haps be best learned by experiment, for by this means the 

 behavior of an organ or organism under a great variety of arti- 

 ficial conditions will be most likely to furnish the clue to the 

 nature of these factors. The hypotheses formulated from such 

 studies can then be subjected to lurther tests, and, if sound, will 

 aid in establishing the science of biology upon the comparatively 

 secure foundation now occupied by the two preeminently experi- 

 mental studies — physics and chemistry. 



It is particularly opportune, therefore, that the results of a 

 large number of the more recent workers in a definite portion of 

 this held have been summarized in this book by Professor Mor- 

 gan. Other portions of the field, such as experimental embryol- 

 ogy, experimental psychology, and experimental study of 

 regeneration (this last also by Professor Morgan), have recently 

 been treated in convenient volumes, while there remains for 

 the present book a discussion of the experimental studies in 

 changes in form of animals. The subject matter naturally 

 divides itself into the six principal topics: Experimental study 

 of evolution, of growth, of the results of grafting, of the 

 influence of the environment on the life cycle, of the determina- 

 tion of sex, and of the secondary sexual characters. Each topic 

 receives critical discussion in Professor Morgan's characteristic 

 and well-known style, and the book is sure to prove a stimulus 

 for further expei'imental work. w. R. c. 



25. The Fauna and Geography of the Maldive and Laccadive 

 Archipelagoes • being the Account of the Work carried on and of 

 the Collections made by an Expedition during the years 1899 and 

 1900 : edited by J. Stanley Gardiner. Pp. 1041-1079 ; v-viii. 

 Volume II, Supplement II, with text-figure 154 and Index I and 



Am. Jour. Sci.— Fourth Series, Vol. XXIII, No. 135.— March, 1907 

 17 



