THE ACCESSORY REPRODUCTIVE ORGANS 271 



ejaculation after all connection with the higher centres had heen cut 

 off. The centripetal nerves for the ejaculatory reflex are the sensory 

 nerves of the penis, the stimulation of the glans being particularly 

 eJEfective.^ 



Erection has been observed to occur in animals which were 

 castrated late in .life, sexual desire in such cases being to some extent 



III. 



Fig. 75. — Diagram illustrating innervation of internal genital organs of 

 male cat. (From Nagel.) 



H., Hypogastric nerve ; Ur., uretei' ; V. D., vas deferens ; II., III., IV., 

 branches arising from 2nd, .3rd, and 4th lumbar nerves. 



retained. It has been shown, however, that erection cannot be 

 induced experimentally in animals which have been castrated prior to 

 puberty ; or, at any rate, that it is far more difficult to cause erection 

 in such animals. Thus, in three experiments carried out by the 

 writer, in conjunction with Professor Sutherland Simpson,^ it was 



' For further references to the literature of the nervous mechanism of 

 erection and ejaculation, see Beonterew, Die Funktionen der Nervencentra, 

 Weinberg!s German Translation, vol. i., Jena, 1908. 



2 Simpson and Marshall, " On the Effect of Stimulating the Nervi Erigentes 

 in Castrated Animals," Qimr. Jour. Exper. Phys., vol. i., 1908. 



