266 THE PHYSIOLOGY OF REPRODUCTION 



and 4th sacral nerves. The stimulation of the 1st and 2nd sacral 

 nerves, on the other hand, generally produced contraction and pallor. 

 Langley obtained similar results in experiments on the male rabbit, 

 the stimulation of the sacral nerves causing either protrusion and 

 flushing of the penis, or else retraction and pallor. 



Nikolski l had previously stated that, on stimulating the anterior 

 ramus of the nervus erigens (or the ramus from the 1st sacral) in 

 the dog, he obtained a vaso-constrictor instead of a vaso-dilator effect, 

 thus differing from Eckhard and other investigators. 



Sherrington 2 found that in the male monkey excitation of the 

 2nd and 3rd sacral nerves produced moderate erection, and that of 

 the 1st sacral only slight erection. In the female monkey the effects 

 of stimulating the 3rd sacral were usually greater than in the case 

 of the 2nd, while the 1st sacral produced no certain effects. Similar 

 results were observed in experimenting on the cat, but in this animal 

 stimulation of the 1st sacral nerve appears to have had a more 

 marked effect. 



Franc/ns-Franck 3 found that the anterior ramus from the 1st 

 sacral was capable of causing both vaso-constriction and vaso- 

 dilatation. This investigator noticed further that both effects could 

 be produced by stimulating the hypogastric nerves, but that the 

 vaso-dilator action was more pronounced. 



Budge 4 also described erector action from the hypogastrics in the 

 rabbit. Langley and Anderson, 5 however, were unable to confirm 

 this statement, but they found that the hypogastrics sometimes 

 contained constrictor fibres for the external generative organs. 



They state that they could discover no satisfactory evidence of the 

 presence of vaso-dilator fibres in any of the upper or lumbar set of 

 nerves. It would appear, therefore, that the vaso-dilator function is 

 probably confined to the lower or sacral set of nerves. 



Following Langley and Anderson's description, the fibres from the 

 sacral set of nerves may be divided into .two groups or classes, the 

 visceral and the somatic. Stimulation of the visceral fibres (which 

 run in the nervi erigentes) produces dilator effects on the vessels' of 

 the penis (and vulva), as already described. It also causes inhibition 

 of the unstriated muscles of the penis, the retractor muscle of the 

 penis (when present), and the unstriped muscles of the vulva (in the 

 female). The somatic sacral nerves send motor branches to the ischio- 

 cavernosus and bulbo-cavernosus muscles, as well as to the constrictor 



1 Nikolski, loc. cit. 



2 Sherrington, "Notes on the Arrangement of some Motor Fibres in the 

 Lumbo-Sacral Plexus," Jour, of Physiol., vol. xiii., 1892. 



3 Fran9ois-Franck, loc. cit. 



4 Budge, loc. dt. 



5 Langley and Anderson, "The Innervation of the Pelvic and Adjoining 

 Viscera," Jour, of Phygiol., vol. xix., 1895. 



