548 



SCIENCE 



[N. S. Vol. XXVI. No. 669 



a complete knowledge of the life histories of 

 all American frogs and toads. E. A. A. 



Behavior of the Lower Organisms. By H. S. 



Jennings. New York, The Macmillan Co. 



1906. Pp. xiv + 366; 144 figs. 



This volume, which is the tenth in the series 

 of biological treatises published by Columbia 

 University, is a timely exposition of the be- 

 havior of the lower organisms by an author 

 who has devoted a large part of his time to 

 an. investigation of this subject. The distri- 

 bution of the materials in the volume follows 

 an admirable plan. The first part of the 

 book deals with the behavior of unicellular 

 organisms, especially Paramecium. The sec- 

 ond part takes up the behavior of the lower 

 metazoans, including the ccelenterates, echino- 

 derms, worms and crustaceans. The third 

 part treats of the theoretic aspect of the sub- 

 ject, and the volume is concluded by a bibliog- 

 raphy and a good index. 



The first and second parts, which are nat- 

 urally more concerned with statements of 

 facts than with speculative matters, are a very 

 full and adequate description of the reactions 

 of the protozoans, lower metazoans, etc., and 

 form, in the reviewer's opinion, the best digest 

 of this subject that has yet appeared. They 

 entirely supersede such recent works as that 

 of Lukas and others, and with their biblio- 

 graphical references they form a most service- 

 able introduction to the subject. 



The third part of the volume is much less 

 happily conceived. This opens with a chapter 

 in which the essential similarity of the reac- 

 tions of unicellular and of multicellular ani- 

 mals is pointed out and the true relations of 

 a nervous mechanism to these reactions is 

 made clear, and it closes with chapters on the 

 development of behavior and the relations of 

 behavior to psychic factors, etc., avowedly 

 hypothetical matters. The body of the third 

 part, however, is taken up with a discussion 

 which turns in the main on a comparison of 

 the tropism theory and the author's own views 

 about animal orientation, etc. It is possibly 

 asking too much to expect an author to make 

 a plea for the opposing side, and yet truth is 



best served by looking facts squarely in the 

 face. Almost no one nowadays, aside from 

 Jennings, would accept the definition of the 

 tropism theory given by him in Chapter XIV^ 

 To be sure, it is easy to find in the older lit- 

 erature the form of the theory that he de- 

 scribes, but practically every one at present 

 who believes in the tropism theory at all has 

 discarded as unessential that portion of it that 

 asserts that the stimulus always influences 

 directly the reacting organ. To retain this 

 and demolish it in the belief that the tropism 

 theory falls with it is rather Quixotic than 

 clear-headed. If the modern tropism theory 

 were as weak as Jennings would have us be- 

 lieve, the experimental evidence upon which 

 it rests ought easily to be explained away. 

 Yet it has always seemed to the reviewer that 

 the characteristic circus movements performed 

 by animals immersed in a homogeneous stimu- 

 lant, but with sense organs unilaterally ob- 

 structed, are explainable only on the basis of 

 this theory. There are other crucial observa- 

 tions in favor of the tropism theory and yet 

 none of these have been satisfactorily ac- 

 counted for by Jennings. 



Jennings is perfectly correct in his insist- 

 ence on the importance of what he formerly 

 called the " motor reaction " as an explanation 

 of the way in which many of the lower ani- 

 mals become distributed or massed, but to 

 prove that this explanation holds in certain 

 cases is not to disprove the tropism theory. 

 The two theories are not mutually exclusive 

 and the processes implied by them may per- 

 fectly well take place at the same time in a 

 given animal. It would seem that Jennings 

 in his enthusiasm for his own views had be- 

 come blinded to the real strength of the 

 tropism theory and not only was unable to 

 accord it fair treatment, but also lacked 

 appreciation of its real value. It is to be 

 regretted that a book excellent in so many 

 particulars should be marred by so consider-^ 

 able a defect. G. H. P. 



SCIENTIFIC JOURNALS AND ARTICLES 

 The American Naturalist for September 

 contains articles on " The Structure of Cilia,., 



