142 CALVIN P. STONE 



tiating the sexes or discriminating between the receptive and 

 the non-receptive female. Since the female makes no vocaliza- 

 tions characteristic of the oestral cycle it may be assumed, there- 

 fore, that these stimuli play no direct part in the arousal of 

 sexual activity in the young male. Experimental results on 

 the control of audition will be given although the data is less 

 conclusive for this sense than for the senses just discussed. 



With rats 23 and 24, which were at this time blind, anosmic 

 and without vibrissae, and had previously been observed to 

 copulate, an attempt was made to prevent audition by destruc- 

 tion of the tympanic membrane of the middle ear and filling the 

 tympanic cavity and the external auditory meatus with melted 

 paraffin. Control tests showed that the animals could hear 

 and localize sounds. Next an attempt was made to destroy 

 the cochlear ganglion by the injection of absolute alcohol into 

 the cochlea. Control tests showed that the ability to localize 

 sounds was greatly impaired, but that there still remained some 

 ability to respond to auditory stimuli. Diffusion of the alcohol 

 along the trunk of the auditory nerve affected not only the 

 auditory sense but also the vestibular apparatus with the result 

 that undesirable interference with the equilibratory mechanism 

 was produced. This complication made it necessary to abandon 

 the method and the problem was dropped temporarily until 

 satisfactory technique for the unequivocal control of the audi- 

 tory receptor could be worked out. 



When tested for copulation, both rats 23 and 24 continued 

 to copulate following the partial destruction of the auditory 

 sense organ, although the equilibratory mechanism was greatly 

 disturbed. 



G. Cutaneous and deep sensibility. Cutaneous and deep 

 sensibility appear to be the most fundamental senses involved 

 in the arousal of the copulatory response. It is probably the 

 medium through which afferent impulses are aroused which 

 cause the definite mounting clasp, erection of the penis pelvic 

 movements whereby the penis is brought into contact with the 

 walls of the vagina, and the other constituent elements of the 

 copulatory response. Ejaculation, likewise is probably brought 



