128 



CALVIN P. STONE 



the first act are presented together with the weight of each rat at 

 the time of the first copulation. The data given in that table 

 show that the earliest age at which copulatory ability was 

 demonstrated was sixty-four days. Probably the normal age 

 falls somewhere between seventy and eighty-five days in the 

 case of well nourished rats. 



Table 13 presents data bearing on the amount of copulation 

 young rats are capable of doing at the time copulatory ability 

 is first manifested. This group of males consists of normal 

 males, semi-vasectomised males, and males with one or more 



TABLE 13 



Copulatory records of young males during periods of time varying from 60 to SO 

 minutes following the initial copulation. The age of the copulating animal is 

 indicated. Also the condition of the rat normal, blind, anosmic or with ductus 

 defer ens of one testicle Ugated is stated. 



receptors removed. No data are available to indicate how fre- 

 quently vaginal entrance is not effected, or an orgasm is not 

 reached. The number of copulatory attempts of the young 

 animal following the initial copulation approximates that of the 

 well nourished adult animal. 



3. Summary 



By way of summary the points brought out in this account of 

 the prepuberal activity of the young male and the initial copu- 

 latory act may be briefly stated as follows : 



