130 CALVIN P. STONE 



exactly with functional sexual maturity as determined by ability 

 to copulate. The normal age at which copulatory ability is de- 

 monstrable is probably between seventy and eighty-five days. 

 The variability, however, in animals reared under practically 

 identical environmental conditions is great. 



10, The young male is capable of copulating approximately as 

 often during a period of thirty minutes following the initial 

 copulation as an adult rat during a similar period of time. The 

 largest number of copulations following the initial act recorded 

 in this study is 51 in thirty minutes. 



STIMULATION LEADING TO COPULATORY RESPONSE 



The results of experimental observation indicate that com- 

 plex congenital behavior is, like the reflexes, conditioned by an 

 hereditary neural organization of receptors and effectors. This 

 hereditary organization differs from that of the reflexes chiefly, 

 if not wholly, in complexity of coordination. Hence it should be 

 possible, because of this close kinship, to subject complex con- 

 genital responses to experimental control in a manner similar to 

 that employed in the study of typical reflexes (Sherrington '06), 

 and, by appropriate variation of technique, to analyse and de- 

 fine their adequate activating stimuli and the operation of the 

 receptor-effector mechanism. In this way there would be brought 

 together the kinds of data needed to give a complete account of 

 the operation of complex patterns of congenital behavior in 

 concrete, objective terminology. 



The literature on congenital responses contains many state- 

 ments concerning the role of external stimulation in the initia- 

 tion of patterns of response. A statement from McDougal's 

 " Social Psychology" 2 illustrates the general type. He says: 

 "In the typical case some sense-impression, or combination of 

 sense-impressions, excites some perfectly definite behavior, some 

 movement or train of movements which is the same in all indi- 

 viduals of the species and on all similar occasions." 



2 Sixth Edition, p. 25ff. 



