SEXUAL BEHAVIOR OF ALBINO RAT 97 



pattern of activity and the serial and functional relationships 

 they manifest, and (2) the kinds of external stimuli adequate to 

 initiate the copulatory act and the manner in which their influ- 

 ences are mediated through the receptors. In a subsequent paper 

 data bearing upon internal factors underlying sexual functions 

 will be presented. 



2. Previous studies of sexual behavior 



It will be of value to consider briefly the experimental studies 

 of sexual behavior of the rat and those of other animals, as well, 

 which have a direct bearing on the present study. This litera- 

 ture will be, therefore, the subject of immediate consideration. 



Banta ('14) gives an excellent account of the mating of the 

 wood frog. Any moving object which came within the radius 

 of several feet attracted the male and caused pursuit. Mascu- 

 line aggression was increased or lessened by the response of the 

 object clasped. The vigorous struggles of a male when clasped 

 by another male were followed by relaxation of the clasp and 

 dismounting of the latter. Frequently several males were 

 seen competing for a single female. If one succeeded in getting 

 into a favorable position on the back of the female and fixed 

 his forelimbs firmly about her he usually succeeded, by vigorous 

 kicks of the hind legs, in forcing other competitors to release 

 their holds. Sexual excitement reached its highest pitch at 

 52F. and was almost wholly wanting at 45F. 



The conjugation of the crayfish was studied by Andrews 

 ('14). He made a very detailed analysis of the pattern of copu- 

 latory acts. Seventeen distinct elements were discovered. 

 Apparently the first elements of the pattern were set off by purely 

 local stimuli afforded by other crayfish in the immediate presence 

 of the male. Through the amputation of bodily structures the 

 author tried to ascertain to what extent the later elements of 

 the act would appear without complete expression of the pre- 

 ceding elements. It was found that the later elements were 

 carried on with as much precision as the animal's imperfect 

 mechanical equipment, due to the loss of essential bodily struc- 

 tures, permitted. Recognition of sex arose through trial at 



