THE ACCESSORY REPRODUCTIVE ORGANS 267 



urethras or deeper muscular stratum of the perineum. In the female 

 they innervate the erector clitoridis, which represents the ischio- 

 cavernosus, and the sphincter vaginae, which embraces the lower end 

 of the vagina, and is the homologue of the bulbo-cavernosus. The 

 sacral nerves, as far as Langley and Anderson l were able to determine, 

 send no visceral fibres by their somatic branches. 



The same investigators found that stimulation of the upper or 

 lumbar set of nerves produced strong contraction of the vessels of the 

 penis, 2 as well as contraction of the retractor muscle, and of the other 

 unstriated muscles of the penis, prepuce, and scrotum (dog, cat, and 

 rabbit). The penis underwent marked retraction as a result of the 

 excitation. Stimulation of the 2nd lumbar nerves in the cat generally- 

 produced a slight but distinct action on the external generative organs. 

 The 3rd, 4th, and 5th lumbar nerves in many cases had a strong 

 action, but the 6th had no action. The 1st lumbar and 13th thoracic 

 were found to have a slight action. In the dog stimulation of the 

 5th lumbar nerve had no effect upon the generative organs, but 

 the 1st lumbar was observed to have a distinct action, and also the 

 13th and 12th thoracic. In the rabbit no effect was produced by 

 stimulating the 1st lumbar nerve. The 2nd lumbar had a slight 

 action occasionally, but the 3rd, 4th, and 5th lumbar nerves always 

 had an effect which was more or less pronounced. 



The fibres from the lumbar nerves run in the white rami 

 conimunicantes to the sympathetic chain, where the}" take two routes. 

 (a) The majority of the fibres take the course of the pudic nerves 

 (nervi pudendi). They follow the sympathetic chain to the sacral 

 ganglia, from which fibres are given off, and these run in the grey 

 rauii communicantes to the sacral nerves. Their further course is by 

 way of the pudic nerves (i.e. in the somatic branches), none apparently 

 running in the nervi erigentes (i.e. to the visceral branches). (5) The 

 second of the courses taken by the lumbar nerve fibres is that by the 

 pelvic plexus. Only a relatively small number, however, take this 

 route. Most of them run in the hypogastric nerves, but a few may 

 join the plexus from the lower lumbar or upper sacral sympathetic 

 chain, or from the aortic plexus. Of these latter, some may join the 

 first root of the nervus erigens, and proceed with it to the pelvic 

 plexus. 3 



It has already been mentioned that the clitoris in the female, like 

 the penis, undergoes erection during coitus. The same is the case 

 with the other parts of the vulva which contain erectile tissue. The 

 friction which is set up between these structures and the glans of 



1 Langley and Anderson, loc. fit. 



2 Vaso-constrictor fibres for the penis were first found by Eckhard (loc. eft.) 

 in the nervus dorsalis penis. 



3 Langley and Anderson, foe. cit. 



