414 



SCIENCE 



[N. S. Vol. XLVI. No. 1191 



tionsliips of convergent types commingled in 

 a common environment and has no basis in 

 critically conducted pure cultures. On the 

 other hand, it is certainly to be expected that 

 more instances of polymorphic life cycles, both 

 obligatory and adaptive, will be discovered 

 when the full histories of green unicells are 

 unraveled. Furthermore, among the Dino- 

 flagellata with certainty, and possibly among 

 the desmids also, there is a high degree of 

 self-regulating control of surface structures 

 leading to a considerable range of form within 

 the species. This is made evident from the 

 fact that in both of these groups there are 

 many species in which at the time of binary 

 fission the daughter organisms each inherits 

 one half of their exoskeleton or cell wall and 

 forms the other half under the influence of 

 the circumambient environment, which in 

 some instances induces a strikingly different 

 form of cell wall, involving structures util- 

 ized as specific characters. These may be of 

 a mutative category, or more evidently of an 

 adaptive or self -regulatory nature. It is also 

 true that the theca or exoskeleton of the Dino- 

 flagellata is subject to autotomy, local ecdysis, 

 total exuviation, and local resorbtion and re- 

 construction to a considerable degree, after 

 its formation, in adaptive response to chang- 

 ing environmental conditions. Such changes 

 are not, however, of the same order of magni- 

 tude as those more profound ones occurring 

 in the transformations in the life history of 

 algse, such as the Palmella stage of the 

 Chlamydomonads. 



On the whole. Professor West's contention 

 as to specific stability seems to be well 

 founded, provided adequate latitude for the 

 metamorphoses of life history is retained and 

 due allowance is made for adaptive and in- 

 volution stages arising under environmental 

 pressure. Both the pure culture method and 

 wide observation of much material of the spe- 

 cies under varying environments are needed 

 to determine the normal range of form. 



The rapid growth of biological literature 

 in the past decades has tended to isolate bot- 

 anists and zoologists, to the detriment of prog- 

 ress in both fields. Professor West's work is 



of great value in facilitating excursions of 

 zoologists into one fundamental and sug- 

 gestive field of botanical research. 



Charles Atwood Kofoid 

 Zoological Laboratory, 

 Universitt or Californla 



A German-English Dictionary for Chemists. 

 By Austin M. Patterson, Ph.D., editor of 

 chemical terms for " Webster's New Inter- 

 national Dictionary " and formerly editor 

 of " Chemical Abstracts." New York, John 

 Wiley & Sons, Inc.; London, Chapman and 

 Hall, Limited. 1917. Pp. xvi + 316. 

 Price $2.00. 



Dr. Patterson's dictionary fulfils a need 

 which probably every English-speaking worker 

 in chemistry has experienced, and fulfils it 

 admirably. The large number of scientific and 

 technical words and the abbreviations which 

 puzzle the beginner in the reading of chem- 

 ical German are all there and the older chem- 

 ist long accustomed to the reading of German 

 chemical literature will experience no less 

 satisfaction in the use of this book, for it is 

 sure to save him much time in determining 

 the exact meaning of the words that even he 

 is apt to find troublesome. The thoroughness 

 with which the dictionary covers the broad 

 field of chemistry as well as such related 

 sciences as physics, mineralogy and pharmacy 

 is very satisfying. Since its appearance in 

 January it has been in constant use in the 

 ofEce of Chemical Abstracts, where transla- 

 ting work involving every phase of theoret- 

 ical and applied chemistry is done and it has 

 stood this test of completeness in such a way 

 as to justify the confidence with which it is 

 used. I say " justify " because, knowing the 

 nature of Dr. Patterson's work on other 

 things and having in mind his experience in 

 handling chemical literature and in compiling 

 the chemical vocabulary and other parts of 

 the New International Dictionary, we expect 

 much. 



In his translations of German names of 

 chemical compounds Dr. Patterson has used 

 care to keep the nomenclature in accord with 

 the best usage. The Introduction, which 

 should be very helpful in several ways, in- 



