144 PHYSIOLOGY CHAP. 



excitation of the nerve, the blood flows from it abundantly with 

 the bright colour of arterial blood. If before the stimulation of 

 the nerve the vena pudenda communis is cut, little blood flows 

 from it ; during stimulation of the nerve the outflow of blood 

 becomes about eight times greater. If the vena dorsalis is cut, the 

 escape of blood becomes fifteen times greater during excitation 

 than it was during rest. All these facts demonstrate that the 

 nervi erigentes are vaso-dilator. 



Love"n (1866) confirmed these results of Eckhard. In addition, 

 he observed that from the small arteries of the penis the blood 

 spurts out with force during excitation of the nervi erigentes, and 

 found in these vessels a notable augmentation of arterial pressure, 

 which even reached six-tenths of that of the carotid. Nikolsky 

 (1879), by introducing a cannula into the dorsal vein of the penis, 

 produced a new confirmation of Eckhard's results, and considered 

 the nervus erigens as an inhibitory nerve analogous to the cardiac 

 vagus. 



More extensive systematic researches on the increase of 

 pressure in the arteries and veins of the penis during erection 

 were carried out by Frangois-Franck (1895), who applied to these 

 inquiries the graphic method already attempted with sparse results 

 by v. Anrep and Cybulsky (1884) and by Piotrowski (1887). 

 Fra^ois-Franck experimented on dogs, introducing into the 

 dorsal artery and vein of the penis in the peripheral direction 

 two cannulae to register manometrically the pressure in them. 

 At the same time he was able to register the changes in the 

 volume of the glans by inserting between it and the prepuce a 

 large glass tube, fixing it there with a ligature, and connecting the 

 narrow end to a Marey recording tambour. 



The result obtained is represented clearly in Fig. 36. In A 

 one sees that stimulation of the nervus erigens produces after a 

 latency of 2^ seconds an -increase of size in the glans, which 

 reaches its maximum 3 to 4 seconds after the stimulation has 

 ceased, and then subsides. 



In B is observed the inverse phenomenon, that is the diminu- 

 tion in volume of the glans following stimulation of the nervus 

 pudendus. In Fig. 37, besides swelling of the glans owing to 

 excitation of the nervus erigens, there are observed the con- 

 temporary increase of pressure in the vein, and the relative 

 diminution of pressure in the artery. This last phenomenon is 

 easily explained when one remembers that the cannula is in the 

 peripheral end of the artery aud is partially emptied during erec- 

 tion, owing to the active dilatation of the lacunar system of the 

 corpus cavernosum, with which it directly communicates. 



During complete erection, owing to the turgidity and lengthen- 

 ing of the penis, its cutaneous integument is passively distended, 

 and the prepuce, through the swelling of the glans, slips behind 



