THE PLAY OF ANIMALS. 243 



indisputable fact. In the first place, it is certain that 

 in general before any important motor discharge there 

 is apt to be a preparatory and gradually increasing 

 excitement. A period of rapidly increasing irritation 

 which causes various reflex movements generally pre- 

 cedes a wrathful onslaught, as angry dogs illustrate no 

 less than Homeric heroes. While we find this introduc- 

 tory stage, which is easy of explanation physiologically, 

 reduced to a minimum in the instinct for flight and in 

 the spring upon prey, it appears to be at the other ex- 

 treme in the courtship of many animals, for we find 

 a long-continued preliminary excitation necessary, which 

 presents strange peculiarities. This fact seems to me to 

 suggest very strongly the probability that in order to 

 preserve the species the discharge of the sexual func- 

 tion must be rendered difficult, since the impulse to it 

 is so powerful that without some such arrest it might 

 easily become prejudicial to that end. This same 

 strength of impulse is itself necessary to the preserva- 

 tion of the species ; but, on the other hand, dams must be 

 opposed to the impetuous stream, lest the impulse ex- 

 pend itself before it is made effectual, or the mothers 

 of the race be robbed of their strength, to the detriment 

 of their offspring. 



If this be granted, all the rest follows easily enough. 

 The most important factor in maintaining this necessary 

 check is the coyness of the female; coquetry is the con- 

 flict between natural impulse and coyness, and the male's 

 part is to overcome the latter. This is accomplished most 

 easily by pursuit, and at last by what appears sometimes 

 as violence, but probably is not really such, but only a 

 necessary stage in the attainment of the requisite pitch of 

 excitation. There are other means as well ; for instance, 

 scent in many animals, that is useful as a means of rec- 



