December 2, 1004.] 



SCIENCE. 



753 



brings out forcibly the fact that almost every 

 reaction of an animal involves or is condi- 

 tioned by the activity of the total organism. 

 The tropism theory is misleading in so far 

 as it seems to suggest that local action, largely 

 independent of the conditions of the body as 

 a whole, is the common rather than the ex- 

 ceptional determinant of reaction. In this 

 portion of the volume it is evident that Jen- 

 nings is emphasizing the unknown factors in 

 animal behavior, while at the same time 

 severely criticizing those observers and 

 theorists who contend that they can reduce 

 organic activity to physical factors. 



Trial and error is the method of adaptive 

 reaction which is most frequently observed in 

 the lower organisms. In a discussion of this 

 topic the author is drawn into a discussion of 

 the meaning of ' error ' : " There is no common 

 thread running through all the different agents 

 which constitute ' error ' in the reaction, save 

 this one, that they are error from the stand- 

 point of the general interests of the organism. 

 * * * Why do we receive without opposition 

 certain chemical stimuli and avoid others? 

 The facts are quite parallel in man and in the 

 lowest organisms in these respects. * * * In 

 both cases the stimuli producing the negative 

 reaction are in general injurious to the or- 

 ganism (p. 247). 



" In ourselves the stimuli which induce the 

 negative reaction bring about the subjective 

 state known as pain, and popularly we consider 

 that the drawing back is due to pain. Is there 

 ground for this view? Or is the reaction en- 

 tirely accounted for by the chemical and phys- 

 ical processes involved? * * * If we hold 

 that in man we can not account for the reac- 

 tion without taking into consideration the 

 pain, then we must hold to the same view for 

 the lower organisms. * * * Any one who 

 holds that we can account fully for the reac- 

 tions of Euglena or Paramecium, purely from 

 the physico-chemical conditions, without tak- 

 ing into account any states of consciousness, 

 must logically hold that we can do the same in 

 man. The method of trial and error implies 

 some way of distinguishing error; the prob- 

 lem is: How is this done? The problem is 



one, so far as objective evidence goes, through- 

 out the animal series" (p. 248). 



The criticism of this volume, as of many of 

 Professor Jennings's other writings, that one 

 is first inclined to make is that there is need- 

 less repetition, that the same simple facts are 

 described and redescribed until one almost 

 feels it an insult to intelligence. But this is 

 a judgment which the author has passed upon 

 himself, for he has elsewhere stated that he 

 describes all his observations in almost pain- 

 ful detail in order that investigators who have 

 cause to use his results may not have the dis- 

 agreeable experience, that has been his often, 

 of failing to find in the description of experi- 

 ments some little point that is important for 

 the problem in hand. Apart from its repeti- 

 tions, the volume is well written; it is also 

 well printed. 



As to the content of the work, it may be re- 

 peated that the evidences of thoroughness, 

 accuracy, fairness to other investigators, free- 

 dom from overhasty generalizing, are such as 

 to inspire great confidence in the results, and 

 to warrant one in believing that they will 

 serve to advance our knowledge of the general 

 subject of animal behavior in a very important 

 manner. In fact, it is not at all improbable 

 that tjiey may necessitate important modifica- 

 tions in the tropism theory. 



EoBpRT M. Yerkes. 



Harvakd University. 



recent books on economic and social science. 



Principles of Economics, with applications to 

 Practical Problems. By Frank A. Fetter, 

 Ph.D. New York, The Century Co. 1904. 



The United States and Porto Rico, with Spe- 

 cial Reference to the Problems Arising out 

 of our Contact with the Spanish-American 

 Civilization. By L. S. Eowe, Ph.D. New 

 York, Longmans, Green & Co. 1904. 



Problems of the Present South. By Edgar 

 Gardner Murphy. New York, The Mac- 

 millan Company. 1904. 



Russia, Her Strength and Weakness, A Study 

 of the Present Conditions of the Russian 

 Empire, with an Analysis of the Resources 

 and a Forecast of its Future. By Wolf 

 VON Schierbrand, Ph.D. New York, G. P. 

 Putnam's Sons. 1904. 



