viii THE PLAY OF ANIMALS. 



put on " tradition," instruction, imitation, etc., in young 

 animals, even in enabling them to come into possession 

 of their natural instincts; in this the book tends in the 

 same direction as the later volume of Prof. C. Llo3'd 

 Morgan. The present writer has also, emphasized the 

 fact under the term social heredity. Again, there is an 

 acute discussion of Darwin's Sexual Selection, a discus- 

 sion which Professor Groos sufficiently explains in his 

 own preface.* I find an anticipation of the position — 

 as it were, a happy intuition — in the Non-Religion of 

 the Future of M. Guyau (page 302. Again, the imper- 

 fect character of most instincts is emphasized, and the 

 interaction with imitation and intelligence. 



Finally, I should like to suggest that a possible cate- 

 gory of " Social Plays '' might be added to Groos' classi- 

 fication; plays in w^iich the utility of the play in- 

 stinct seems to have reference to social life as such. In 

 such a category it might be possible to place certain of 

 the animals' performances which seem a little strained 

 under the other heads; and also those performances in 

 which the social function of commwiication is playfully 

 exercised. A good deal might be said also in question of 

 the author's treatment of " Curiosity " (Neugier) . He 

 makes curiosity a matter of the attention, and finds 

 the restless activity of the attention a play function. 

 My criticism would be that w^hile curiosity does bring 

 the animal into possession of the details of knowledge 

 before they are pressed in upon him by harsh experience, 

 yet attention does not altogether fulfil the requirements 

 of the author's psychological theory of play. 



* " Sexual " is referred back to " natural " selection. althouc:h 

 the direct results of such preferential matine: would still seem to 

 be a " determination " of variations for natural selection to work 

 upon {cf. Science, November 23, 1896, p. 726). 



