49 8 



THE QUARTERLY REVIEW OF BIOLOGY 



comparative psychology and in taking in 

 general an objective attitude in matters 

 of interpretation he showed himself to be 

 several decades ahead of his time. 



The early work of Verworn (2-17) and 

 of Loeb (161) on the lower organisms was 

 a continuation of that of the botanists, 

 anatomists, physiologists and zoologists 

 of the preceding period. Following the 

 excellent work of Engelmann (127, iz8) 

 and others, Verworn carried out the most 

 thoroughgoing investigation of unicell- 

 ular forms that had been made up to that 

 time. His experimental findings were 

 brought together in the Protisten-studien 

 (1889), which occupied much the same 

 position then as the well known volume 

 of Jennings C I 49) does at present. Ver- 

 worn emphasized the apparently spon- 

 taneous, or internally stimulated activity 

 of unicellular forms, while insisting upon a 

 physico-chemical explanation of their 

 behavior. It is true that he indulges in 

 speculation which suggests the influence of 

 Haeckel's monism, but this is entirely 

 absent in his later volume (1894). Here 

 (zi8) he gives a clearer and more straight- 

 forward statement of his tropism theory 

 and of his general view regarding the 

 nature of the behavior of organisms. He 

 differed from the more radical position of 

 Loeb in much the same way that Jennings, 

 his pupil, came to differ later. 



Loeb began his work on the plant-like, 

 sessile Coelenterates and was the first to 

 make extensive use in the analysis of 

 animal behavior of technique similar to 

 that developed earlier by the botanists. 

 Taking his cue from the tropism studies of 

 the plant physiologists, he attempted to 

 determine to what extent the orientation 

 responses of lower animals to external 

 stimuli could be described and explained 

 on a similar basis. He was led to the 

 conclusion that most, if not all, of the 

 behavior of lower animals was tropistic in 



much the same sense as that of plants, 

 and therefore unconscious. The physico- 

 chemical explanation of Loeb was new and 

 startling, primarily because of his insist- 

 ence that lower organisms react wholly on 

 the non-psychic level. This point was 

 generally conceded insofar as the plant 

 kingdom was concerned — fortunately the 

 anecdotalist and the philosopher had, in 

 the main, kept aloof from the lowly plant. 



The new view, and particularly the 

 tropism theory of Loeb, was little short 

 of a complete return to the mechanistic 

 position of Descartes, and came as a fatal 

 shock to the post-Darwinian humanizers. 

 This bold attempt to analyze the behavior 

 of lower organisms by physiological 

 methods and to explain it in purely 

 objective terms was little short of heroic 

 in view of the anthropomorphic babblings 

 of the times. It was, indeed, a far crjl 

 from the notion of Romanes that the] 

 insect flies into the candle flame out of an 

 innate curiosity to the contention of Loeb' 

 that it is forced to do so in a very literal | 

 sense when presented with the appropriate ; 

 external stimulus. Among other criti-.' 

 cisms of Loeb's theory the satirical attack 

 of Claparede (118) is interesting. Hei 

 pointed out that an observer from a distant 

 planet might well suppose that human 

 activity was also largely tropistic and be 1 , 

 led to speak of the doctor-tropism, corpse-: 

 tropism, food-tropism, etc. of mankind.! 

 Somewhat later Nuel (183) made a direct 

 application of the tropism principle to the» 

 behavior of man in a thoroughly serious 

 but unconvincing manner (zoi). 



From the work of Loeb, as Brett 

 remarks, ' 'arose a new type of comparative^ 

 psychology, the mechanistic school o|j 

 Bethe, vonUexkull,Th. Beer and Ziegler: 

 for these writers the higher animals hav« 

 consciousness, the lower do not." This 

 group of physiologists were mainly 

 interested in experimental work upon the 



