SEXUAL BEHAVIOR OF ALBINO RAT 109 



is believed that the samples, taken collectively, give a very fair 

 picture of the general nature of the activity of the young rat in 

 the company of the female at various ages prior to sexual ma- 

 turity. It, will, therefore, serve as a tentative basis for the 

 consideration of permature sexual behavior. 



A. Prepuberal behavior. Tables 2 to 11 give the data for each 

 of the eight rats used in the study. Rats 50 and 54 were observed 

 daily. On alternate days an adult male was substituted for the 

 female. The other six animajs were observed on alternate days, 

 and with females only. The data for two consecutive observa- 

 tions have been combined and averaged in order to condense the 

 results somewhat, thereby giving a more compact picture of the 

 types of behavior to which attention will be called. The num- 

 bers give the time in seconds spent by each rat during twelve 

 minutes doing a particular act or class of acts grouped under a 

 heading of the category. 



For the purpose of briefly considering the relation of the fore- 

 going prepuberal activities to the copulatory act they may be 

 thrown into two groups: (a) A group of non-sexual, or acts that 

 are obviously unrelated to the copulatory act; and (b) a group of 

 acts that appear to be connected with the copulatory act but 

 are really not so connected. Under these headings the chief 

 facts brought out in the two series of observations may be 

 considered. 



a. Non-sexual activities. The young rat, twenty-one days of 

 age, gives attention to the adult female as soon as the latter is 

 placed in the cage. It approaches without fear and precedes 

 to explore such parts of her body as are within reach. From 

 three to five days later it climbs upon her back, if she sits quietly 

 in the cage, and extends the general exploration to the back, 

 neck and top of her head. Sniffing in the region of the mammary 

 glands is seen occasionally at or a few days after the age of twenty- 

 one days, but only rarely after twenty-five days. The greater 

 part of the tune during the first five to ten minute is spent in 

 nosing about the head of the female, licking her body, and search- 

 ing for parasites (Nibbling, tables 2 to 11.) This holds true for 

 all ages from the time of the first observtions to the last. While 



