96 ANIMAL-SENTIENT FORCES. [r. 



177. The organs of the external senses, considered as me- 

 chanical machines only (155) are subject to the same laws as 

 others. Through external sensations, sensational conceptions, 

 instincts, emotions, and even through the will, the nerves cause 

 movement in the tongue, the nose, the ears, the eyes — even the 

 skin in which are placed the nerves of touch, is contracted by 

 many external sensations (as cold); all which movements are 

 true sentient actions. 



178. The sexual organs of man, and especially the testes and 

 penis, are supplied with numerous and large nerves, which are 

 extremely sensitive. The sensibility of the testes is so great, 

 that syncope and convulsions are induced by injuries to them, 

 and locked jaw, in particular, from the sympathy of their 

 sentient actions. The sensitive nerves of the penis, which every 

 impression excites, afford a remarkable example of the action 

 of conceptional impressions on the vessels through the nervous 

 loops around them, and independently of muscular action, of 

 which mention has been already made (160), for the tume- 

 faction of the corpora spongiosa must be caused by a reten- 

 tion of the blood in the vessels ; which can only be explained 

 by the theory that the nerves induce the vessels to contract, 

 in fact, this tumefaction is excited by every kind of external 

 impression on these nerves, especially by external sensations, as 

 when urine irritates the bladder; semen the seminal ducts; 

 the venereal poison, and Spanish flies the urethra, — which is 

 very sensitive; and other causes, as flogging, and friction of 

 the glans penis. In like manner, it is caused by imaginations, 

 foreseeings, sensational desires, instincts, and emotions, as is 

 well known, and altogether independently of the will. Haller 

 maintains the doctrine, that this swelling takes place without 

 the assistance of the muscles, and solely by the blood-vessels, 

 finding analogous instances in the erection of the nipples in 

 sucking, the distension of the wattle of the turkey, and of the 

 organs of generation in lower animals ('Physiology,' § 840), 

 all which are sentient actions. (Compare § 274.) 



179. The numerous nerves distributed to the female organs 

 of generation, render them extremely sensitive, and the re- 

 marks in the preceding section are equally applicable to 

 them (274). 



180. It is the most important mechanical machines of animal 



