MALE ACCESSORY REPRODUCTIVE ORGANS 253 



When it contracts it causes a marked dorsal curvature of the 

 penis.^ 



Although the sexual orgasm is usually accompanied by a 

 high degree of mental excitement, it is essentially a reflex action, 

 and can take place when aU connection with the brain is severed 

 by transection of the spinal cord. It is generally believed that 

 the centre for erection Hes in the lumbo-sacral region of the 

 cord.^ Numerous experiments have been recorded which prove 

 conclusively that it is not situated in the upper part of the cord 

 or in the brain. Thus, Goltz * showed that transection of the 

 spinal cord above the lumbar region did not destroy the reflex. 

 Brachet * also has recorded the occurrence of ejaculation vmder 

 a similar condition. According to Miiller,* only the lower part 

 of the cord need be retained in order to preserve the erection 

 reflex, since this is still present after the complete destruction of 

 the cord in the whole of the lumbar and the upper part of the 

 sacral region. Miiller was able to induce erection in a dog, 

 which had undergone this operation, by rubbing the surface 

 of the penis. 



It is known, however, that erection (and even ejaculation) 



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

 Viscera: Part III. The External Generative Organs," Jour, of Phys., vol. xix., 

 1895. The retractor muscle is remarkable for its sensitiveness to changes of 

 temperature, and at the same time for being unusually tenacious of life. It 

 can be cut out of the body and preserved in blood serum, in a cool place, for 

 days at -a time, and afterwards, on warming, will relax and undergo spontaneous 

 contractions. At a temperature of 40° C. it is quite placid ; but, on cooling 

 slightly, it will shorten, and not infrequently enter into a series of slow 

 rhythmic contractions. If cooled to 15° C. it will contract to about one 

 quarter of its original length. (Sertoli, " Contribution h. la Physiologie 

 G^nferale des Muscles lisses," Arch. Ital. de Biol., vol. iii., 1883 ; Gruenhagen, 

 "Das Thermotonometer," Pfiiiger's Arch., vol. xxxiii., 1884. See also 

 Fletcher, "Preliminary Note on the Motor and Inhibitory Nerve-Endings 

 in Smooth Muscle," Proc. Phys. Soc, Jour, of Phya., vol. xxii., 1898.) 



" See Onnf, "Notes on the Arrangement and Function of the Cell 

 Groups in the Sacral Region of the Spinal Cord," Jour, of Nervous and 

 Mental Diseases, 1899. 



' Goltz, " Ueber das Centrum der Erectiousnerven," PJlilger's Arch., 

 vol. vii., 1873. See also Goltz and Frensberg, "Ueber die Functionen des 

 Lendenmarks des Hundes," PflUger's Arch., vol. viii., 1874. 



* Brachet, Recherches experimentales sur les Fonctions du SyaUme Nerveux 

 Qanglionaire, Paris, 1839. 



* Mtiller, " Klinische und Experimentelle Studien iiber die Innervation der 

 Blase," &c., Deutsche Zeitachr. f. Nervenheilk. , vol. xxi., 1902. 



