590 'Journal of Comparative Neurology and Psychology. 



illusti'ation, tlie gradual weakening of pbototi"opism in an animal placed 

 before a lighted window is cited, but certainly in such a case, where the 

 stimulus is continuous, we often find not a weakening but an intensification 

 of the tropism, as Holmes observed in Ranatra. By the way, it was surely 

 a slip to represent, on page 187, the righting reaction of a planarian as an 

 illustration of spiral movement which "facilitates progression through the 

 water." 



The most interesting sections of the book are those dealing with "associa- 

 tion." As has been said, Bohn holds "associative memory" to be the criterion 

 of the "psychic." But a person who approaches comparative psychology from 

 the starting-point of a psychologist finds great difficulty in coming to an 

 understanding with one who sets out from the biological side, in regard to 

 the meaning of the term "psychic." To the former the term psychic implies 

 consciousness. Sometimes, it is true, we find "functioual" psychology talking 

 of sensations when it means sensory physiological processes without any 

 subjective aspect, but in general the psychologist uses psychological terms for 

 mental processes only. The case is otherwise with the biologist. Bohn says 

 that he himself means by such terms as sensation, "not the facts of con- 

 sciousness, inaccessible to me, but the nervous processes upon which they are 

 superposed." Elsewhere he remarks, "The sensation iu the psychological 

 sense is an epiphenomenou, true ; but as such it is superimposed upon 

 another phenomenon which takes place in the nervous system, which is 

 amenable to experimental study, and which is often called sensation ; which 

 may be so called if one specifies that the word is taken in a physiological 

 sense. The word sensation does not necessarily imply consciousness." So 

 far as this word, indeed, is concerned, we need not, perhaps, be overscrupu- 

 lous, for the mere response to a sensory stimulus does not, to our author 

 and to Loeb, involve "the psychic ;" but Bohn's expressions, and his adoption 

 of association as a test of the psychic, certainly imply that there is such a 

 thing as a psychological aspect to animal behavior. What is the psychic, 

 which is not necessarily involved in sensation, but of whose presence "associa- 

 tive memory" assures us? It is certainly puzzling to have Bohn, in expound- 

 ing Loeb, tell us that "the latter does not deny psychic phenomena in the lower 

 animals ; for him, these phenomena are physiological reactions which result 

 from associative memoi-y." We are, however, used to the confusion of psy- 

 chological and physiological in Loeb's case; but Bohn is writing genetic psy- 

 chology, and the psychologist is saddened when he reads such a statement as 

 this : "I shall not speak here of the consciousness of animals. I do not deny 

 it, but I cannot know anything about it. I shall speak of psychism, the word 

 designating the complexity of phenomena which I can more or less success- 

 fully analyze." Why talk about the criterion of the psychic, an epiphenom- 

 enon superimposed upon certain nervous processes, if you mean by "psychic" 

 only the nervous processes themselves? It is indeed interesting to note that 

 they sometimes reach a certain degree of complexity, and one may call them 

 "associative memory" when they do, if one's sense of the fitness of names is 

 not acute, but they are evidently not a criterion of anything but themselves, 



