Literary Notices. 95 



ior under natural conditions and food habits. The next two chapters are given to 

 the behavior of lower Metazoa. The behavior of ccelenterates receives very full 

 treatment. Summing up his conclusions from the study of behavior in these relatively 

 simple multicellular organisms the author says: "Comparing the behavior of 

 this low group of multicellular animals with that of the protozoa, we find no radi- 

 cal difference between the two. In the ccelenterates there are certain cells — the 

 nerve cells — in which the physiological changes accompanying and conditioning 

 behavior are specially pronounced, but this produces no essential difference in the 

 character of the behavior itself. " The treatment of other metazoan forms occupies 

 but a single chapter and is topical rather than systematic in form. This brings us 

 to the end of the descriptive portion of the book. 



The objective point of view is very carefully and consistently maintained in 

 these descriptive chapters. Though treating of a variety of topics, they have never- 

 theless a very definite unity. This comes about through the marked emphasis 

 which the author puts upon certain features which he has found to be common to 

 the behavior of all the lower organisms so far investigated. Of these common fea- 

 tures the following are the ones on which greatest stress is laid: 



1. Organismschange their behavior(i. ^., react) in response to changes in exter- 

 nal conditions. "The most general external cause of a reaction is a change in the 

 conditions affecting the organism." 



2. The character of the behavior of an organism under any particular set of 

 external conditions is not determined solely by those external conditions but to as 

 great or even to a greater degree by internal conditions (the "physiological state" 

 of the organism). 



3. The behavior of all organisms is, generally speaking, of a markedly adap- 

 tive character. 



4. The most usual mechanism by which this adaptiveness in behavior is 

 brought about is that of the "trial and error" method of response to stimuli. "We 

 find behavior largely based on the process of performing continued or varied move- 

 ments which subject the organism to different conditions of the environment, with 

 selection of some and rejection of others." 



5. Behavior is in general not a fixed or stereotyped character, but instead is 

 capable of varying degrees of modification under different circumstances. On the 

 whole modifications so induced are of an adaptive character. 



In the opinion of the reviewer the clear and conclusive demonstration that the 

 features enumerated are common to the behavior of all the lower organisms hitherto 

 investigated in detail is a great achievement of the book. The thing most lacking 

 in animal behavior work hitherto, has been a unified standpoint leading to the 

 elucidation of the features of behavior which were general (that is, common to a 

 wide range of organisms). 



Turning now to the theoretical portion of the book, we have first a short chapter 

 (XIII) comparing the behavior of unicellular and multicellular organisms. The 

 author's general conclusion is that there are no differences of fundamental character 

 in the behavior of the Protozoa and Metazoa. He is strongly inclined towards the 

 view as to the function of the nervous system which has been upheld by LoEB; 

 namely,that it has no exclusive functions not primitively common to all protoplasm. 

 The next chapter is devoted to a convincing destructive criticism of the "tropism 

 theory." The author's views on this subject are so well known that special com- 



