Recent Biology 383 



seem a little strained under the other heads — for example, those 

 performances in which the social function of co7nmuniaition is 

 exercised early in life. A good deal might be said also in ques- 

 tion of the author's treatment of ' Curiosity ' {Nengicr). He 

 makes curiosity a function of the attention, and finds the restless 

 activity of the attention a play function, which brings the animal 

 into possession of the details of knowledge before they are pressed 

 in upon him by harsh experience. My criticism would be that 

 attention does not fulfil the requirements of the author's psycho- 

 logical theory of play, as indicated below. 



Turning now to the interesting question of the psychological 

 theory, we find it developed, as it would have to be, in a much 

 more theoretical way. The play consciousness is fundamentally 

 a form of ' conscious self-illusion ' (pp. 311 fT.) — Imvussk Sclbst- 

 tduschung. It is just the difference between play activity and 

 strenuous activity that the animal knows, in the former case, that 

 the situation is not real, and still allows it to pass, submitting to 

 a pleasant sense of illusion. It is only fair to say, however, that 

 Herr Groos admits that in certain definite instinctive forms of 

 play this criterion does not hold ; it would be difficult to assume 

 any consciousness of self-illusion in the fixed courting and pair- 

 ing plays of birds, for example. The same is seen in the very 

 intense reality which a child's game takes on sometimes for an 

 hour at a time. Indeed, the author distinguishes four stages in 

 the transition from instincts in which the conscious illusion is 

 absent, to the forms of play to which we can apply the phrase 

 ' Play activity ' in its true sense, i.e., that of Schcijithatii^kcit 

 (pp. 298 f.). The only way to reconcile these positions that I see 

 is to hold' that there are two different kinds of play — that which 

 is not psychological at all, i.e., does not show the psychological 

 criterion at all, and that which is psychological as Scheinth'dtii::;- 

 keit. Herr Groos does distinguish between ' objective ' and 

 'subjective' Scheinthdtigkeit (p. 312). The biological criterion 

 of definite instinctive character might be invoked in the former 

 class, and the psychological criterion in the other. And we 

 would then have a situation which is exemplified in many other 

 functions of animal and human life — functions which are both 



