THE ACCESSORY REPRODUCTIVE ORGANS 255 



and for pain ; as soon then as the water at 45 C. covered the corona 

 without reaching the foreskin, both cold and pain disappeared, giving 

 place to an exquisitely pleasant sensation of heat." " In none of 

 these cases was the process of selective inhibition in any way conscious. 

 The sensation evoked was a definite one of heat, of cold, or of pain, 

 but it was the final issue of a struggle between incompatible and 

 mutually antagonistic afferent impulses." 



The arteries of the penis are the internal pudic arteries and the 



T.A. , 



7. 



Corp. 



Spomj. 



Tt. Subf. 



' A. 



T. A. 



U. 



FIG. 67. Transverse section through adult human penis. 

 Eberth, from Nagel.) 



x 3. (After 



A., Artery ; C., cutis ; Com., communication between the two corpora 

 cavernosa ; Corp. 8pong., corpus spongiosum ; F., fascia ; J r ., nerves ; 

 S., septum ; T. J., tunica albuginea ; Te. Subc., tela subcutanea penis ; 

 Te. Subf., tela subfascialis ; Tun., tunica dartos penis ; Tr., trabeculte 

 of corpus cavernosum ; U., urethra ; V., veins. 



dorsal artery. Some of the arterial branches project into 'the 

 intertrabecular spaces of the corpora cavernosa, and form coiled dilated 

 vessels which are known as the helicine arteries. In these arteries 

 the intima is folded, thus rendering them capable of great dilatation. 

 Moreover, these arteries present here and there a thickening of the 

 intiina in the form of little cushions which constitute a valvular 

 apparatus which limits the flow of blood into the corpora cavernosa, 

 when the muscular coat assumes the tonus that exists when the penis 

 is flaccid. 1 In most cases the arteries are said to open into the venous 

 spaces, through the intervention of capillaries, but a few of the 



1 Luciani, loc. cit. 



