142 



NATURE 



[May 11, I'd I 



Protozoa the rcs|)on»c to stimuli exhibited by their 

 protoplasm is not simply one of reaction to external 

 stimuli, but is of such a nature that a purposive 

 function seems to be postulated, and that protoplasm, 

 even in very lowly forms, as undoubtedly is the case 

 in higher ones, is able to store impressions — possesses, 

 in fact, the rudiments of a memory. From the un- 

 difTerenliated condition, the next step forward is the 

 development of a rudimentary nervous system, such 

 as occurs in the sponges, then the development of 

 well-marked nervous tissue, its aggregation into gang- 

 lionic masses, and eventually the formation of a 

 definii'- though simple nervous system is traced 

 thri.i invertebrates, and, finally, the progres- 



siv»- I Muuiii.ii of a nervous system through the verte- 

 brates, culminating in man with his elaborate 

 psychical processes. 



Although some would hold that the response of 

 protoplasm to external stimuli is simply one of 

 reaction, we think that the author's view of purposive 

 action in addition is borne out by the facts cited, and 

 that this is inherent in protoplasm, just as the tend- 

 ency to variation appears to be. With regard to the 

 second part of the book, we are not in a position to 

 criticise its historical accuracy, but it makes interest- 

 ing reading. The emotional and instinctive qualities 

 displayed by the Irish Celts depends, according to 

 the author, on their hereditary characters rather than 

 on experience and on intellectual acquirements. The 

 b(X>k is pleasant and instructive reading, and though 

 here and there not altogether free from error, on the 

 whole is a simple and well-developed exposition of the 

 subject of which it treats. 



ANIMAL PSYCHOLOGY. 



(i) L'Evolution de la Mimoire. . By Henri Pi^ron. 



Pp. 360. (Paris : Ernest Flammarion, 1910.) 



Price 3.50 francs. 

 (2) YorXesungen iiber Ticrpsychologie. By Prof. 



Karl Camillo Schneider. Pp. xii4-3io. (Leipzig: 



W. Engelrnann, 1909.) Price 8 marks, 

 (i) \/T PIERON'S book is a new addition to that 

 •*■'-■■. excellent and deservedly famous series, the 

 " Biblioth^que de Philosophic scientifique," and is 

 quite worthy of its place. Its subject is, to say the 

 least, a difticult one, being dependent on the careful 

 interpretation of vast quantities of scattered observa- 

 tions and researches made by students of comparative 

 psychology during quite recent years ; but M. Pi^ron 

 has produced out of this material, some of which is 

 furnished by researches of his own, a volume which 

 is not only compact and thoroughly sound, but also 

 readable. 



In an excellent introduction, he criticises certain 

 definitions of memory that have been held in the 

 past, and shows by the help of numerous and in- 

 teresting examples the continuity, the complete lack 

 of hiatus, in the succession of phenomena commenc- 

 ing with the inorganic memory shown in viscosity, 

 hysteresis, &c., through biological memor}', heredity, 

 adaptation, &c., to psychological memory, which is 

 frequently alone allowed the designation memory. 

 NO. 2167, VOL. 86] 



The presence of consciou»ne»» in psycholo^^. 1 

 memory U important, but not of that essential sifiiu- 

 ficancr which the more metaphysically-minded among 

 the psychologists are so fond of attributing to it. 

 This is quite clearly shown in researches on thu 

 memorising of nonsense syllables (Ebbinghausj 

 where the curve representing the number of repetitions 

 necessary for completely learning series of var)ing 

 lengths is found to belong to the same type, to have 

 the same mathematical equation, as that representing 

 nuinomolecular autocatalytic reactions in chemistry, 

 viz., \ogx = Kl + b. 



.The contrast, in fact, is not between subhuman 

 .iiffl human memory, but one between memory as it 

 is for the individual himself aS he enjoys it in con- 

 sciousness, and memory as it t^anifests itself objec- 

 tively both in himself and in his fellow-man. 



The author proceeds to consider the phenomena 

 more in detail, commencing with an interesting 

 description of the " persistances rythmiques " dis- 

 played by both plants and animals. In the case of 

 the latter, the best examples are given by marine 

 animals, which live on the seashore and reproduce 

 in their organic functions the rhythm of the tides. 

 The rhythm persists when the animals are removed 

 to a new, non-rhythmical environment, although an 

 observer has found that this is not the case with 

 young individuals that have not experienced the tidal 

 rhythm. Pieron has some interesting comments and 

 criticisms to make on the whole problem. 



There follows a clear and concise account of the 

 modern experimental methods of research employed 

 to investigate the processes of adaptation and the 

 formation of habits in animals, and the important 

 researches of Thorndike, Hobhouse, Yerkes, and 

 others are usefully summarised. A chapter on 

 " sensory memory," full of experimentally determined 

 results, completes the part of the volume allotted to 

 subhuman psychology. 



The last hundred pages of the book deal with 

 specifically human memory, and summarise in small 

 space an enormous number of experimental investiga- 

 tions. The author points out that the laws of rate 

 of learning and forgetting admit of identical mathe- 

 matical expression for animals and for men, for the 

 different forms of sensorial and motor memory, &c. 

 The curves correspond to the same general mathe- 

 matical formula, viz., y=A/K-B*. The non-corre- 

 spondence of memory and intelligence is noted, and 

 pathological modifications are adequately treated. 

 With a useful chapter on the utilisation of memon.-, 

 and a conclusion, written in more speculative mood, 

 the book ends. 



(2) Prof. Schneider gives in his series of published 

 lectures a very full and decidedly original account of 

 the subject-matter of animal psycholog}-. Regarding 

 the physiological mechanism of the nervous system 

 as capable of producing summation of stimuli only, 

 he finds himself forced to assume an active and 

 efficient " Psyche " to explain most of the phenomena 

 of his science. " Die Psyche assoziiert die einzelnen 

 Eindriicke, die dabei ihre Selbstandigheit wahren 

 (.\ssoziationsorgan), wahrend das Gehirn sie sum- 



