THE AMEBIC AN NATURALIST [Vol. XLVI 



developed than seems desirable, but in compensation the sec- 

 tions on biology and experimental subjects such as regenera- 

 tion, regulation, grafting, graft hybrids, effects of external fac- 

 tors on growth and regeneration, polarity and heteromorphosis 

 are well, though concisely, developed. Several pages of prac- 

 tical suggestions as to collection, rearing, feeding and preparing 

 Hydra will be found very useful as will also the key to the 

 species. The author conservatively clings to the widely current 

 names viridis, grisea and fusca and rejects the older names of 

 Piill.-is which strictly have priority. 



Half of the book is given to the hydroids. Noteworthy in this 

 are several superb figures of hydroid colonies from the Hel- 

 goland Nordsee Museum. A brief list of titles closes the volume 

 from which we note the omission of Nutting's and Mayer's 

 monographs. 



The vol nme by Professor Meisenheimer upon the garden snail 

 follows closely the program of the series, with perhaps less of 

 emphasis upon the experimental and physiological aspects and 

 more space taken for the presentation of the static phases which 

 are greatly increased necessarily over those of a simple animal 

 such as Hydra. But there appears still to be call for more 

 expansion on the dynamic aspects of the subject in the case of 

 this volume. The chapter upon the relation of the snail to the 

 environment and to man is a concession in the right direction, 

 and the prevalence of the biological standpoint throughout the 

 anatomical chapters in some measure supplies the physiological 

 data pertinent to the structural phases. These are very clearly 

 and methodically set forth with abundant illustrations, many 

 of which are new. A chapter on other land pulmonate mollusks 

 affords an all too brief basis for comparison of the snail with 

 other mollusks. 



Roth of these volumes will be exceedingly useful to zoologists 

 in all countries, for the objects with which they deal are cos- 

 mopolitan. A similar series of monographic booklets on labo- 

 ratory types based on American material would be of great 

 value for American students and investigators. 



Charles Atwood Kofoid 



