a tp ee we ea PHYSIOLOGY. 179 
SECTION XxX. 
Irritability of the Penis. 
ecccxLi. The penis is a spongy fibrous sub- 
stance, composed of the glands, urethra, and cor- 
pora cavernosa ; in general it is soft and pendulous, 
but in erection hard and rigid. The hardness of 
the penis proceeds from a sudden expansion of its 
cavernous texture, which is at the same instant 
filled with blood from the pudic arteries. Expan- 
sion of the penis arises most commonly from 
sympathy with the brain and testicles. 
cccextiv. Castration has been long known to 
prevent the growth of the cervical muscles of 
male animals, but Gall was the first to detect an 
intimate relation between the cerebellum and the 
genital organs. The intensity of the venereal 
appetite is found to vary according to the deve- 
lopement of the cerebellum: when this organ is 
inflamed, it often causes the most distressful 
priapism. Even in a case where a patient had 
been reduced by previous disease, I have known 
inflammation of the cerebellum produce the most 
