348 



SCIENCE, 



LN. S. Vol. V. No. 113. 



With this general and inadequate notice of 

 the divisions and scope of the book, I may throw 

 together in a few sentences the main theoretical 

 positions to which the author's study brings 

 him. He holds play to be an instinct developed 

 by natural selection (for he does not accept the 

 inheritance of acquired characters), and to be 

 on a level exactly with the other instincts 

 which are developed for their utility. It is very 

 near, in its origin and function, to the instinct 

 of imitation, but yet they are distinct (a word 

 more below on the relation between play and 

 imitation). Its utility is, in the main, two-fold : 

 First, it enables the young animal to exercise 

 himself beforehand in the strenuous and neces- 

 sary functions of its life and so to be ready for 

 their onset ; and second, it enables the animal 

 by a general instinct to do many things in a 

 playful way, and so to learn for itself much 

 that would otherwise have to be inherited in 

 the form of special instincts ; this puts a premium 

 on intelligence, which thus comes to replace 

 instinct (65f.). Either of these utilities. Professor 

 Groos thinks, would insure and justify the play 

 instinct ; so important are they that he suggests 

 that the real meaning of infancy is that there 

 may be time for play.* 



It is especially in connection with this latter 

 function of play that the instinct to imitate 

 comes in to aid it. Imitation is a real instinct, 

 but it is not always playful ; play is a real in- 

 stinct, but it is not always imitative. Professor 

 Groos does not suggest, I think, closer relations 

 between these two instincts. There is likely, 

 however, to be a great deal of imitation in play, 

 since the occasion on which a particular play 

 instinct develops is often that which also de- 

 velops the imitative tendency as well, i. e. , the 

 actual sight or hearing of the acts and sounds 

 of other animals. Moreover, the acquisition of 

 a muscular or vocal action through imitation 

 makes it possible to repeat the same action 

 afterwards in play. 



It is only a step, therefore, to find that imita- 

 tion, as an instinct, has to have ascribed to it, 



* " Die Thiere spielen nicht weil sie jung slnd, son- 

 dern sie liaben eine Jugend, weil sie spielen miisseu " 

 (68). Other capital utilities which might be added 

 are (1) the exercise o£ the intelligence itself and (2) 

 direct social utility as such. 



in a measure, the same race utility as play — that 

 of going before the intelligence and preparing 

 the way for it, by rendering a great number of 

 specialized instincts unnecessary. It is inter- 

 esting to contrast this view with that which 

 the present writer has recentlj'^ developed in 

 these pages (Science, March 20, 1896), i. e., 

 the view that imitation supplements inadequate 

 congenital variations in the direction of an in- 

 stinct and so, by keeping the creature alive, 

 sets the trend of further variations in the same 

 direction until the instinct is fully organized 

 and congenital. If both these two views be 

 true, as there seems reason to believe, then 

 imitation holds a remarkable position in rela- 

 tion to intelligence and instinct. It stands mid- 

 way between them and aids them both. In 

 some functions it keeps the performance going, 

 and so allows of its perfection as an instinct ; in 

 others it puts a stress on intelligence, and so 

 allows the instinct to fall away if it have no in- 

 dependent utility in addition to that served by 

 intelligence.* In other words, it is through 

 imitation that instincts both arise and decay — 

 that is, some instincts are furthered and some 

 suppressed, by imitation. And all this is ac- 

 complished with no appeal to the inheritance of 

 acquired characters. Professor Groos agreeing 

 with Weismann that the operation of natural se- 

 lection as generally recognized is sufficient. 



The difficulty which I see to this conception 

 of play as a pure instinct is that which is some- 

 times urged also against considering imitation 

 an instinct, i. e., that it has no definite motor 

 coordinations, but has all the variety which the 

 different play forms show. If the definite con- 

 genital plays are considered each for itself, then 

 we have a great many instincts, instead of a 

 general play instinct. But that will not do, for 

 it is one of Professor Groos' main contentions, 

 in the chapter on the psychology of animal 

 plays, that they have a common general char- 



* In a private communication Professor Groos sug- 

 gests to me that the two views might be held to 

 supplement each other. Tlie case is very much like 

 that of early intelligence, in the form of association; 

 where it fully accomplishes the utility also subserved 

 by an instinct, it tends to supersede the instinct ; oth- 

 erwise, it tends to the development of the instinct 

 (Groos, p. 64). 



