388 ORGANS OF THE SENSES. 



substance. The presence of bodies in these organs is often 

 only discovered after death. The pulmonary surface, pro- 

 perly so-called, appears to be the seat of agreeable sensations 

 (breathing pure air) as well as disagreeable ones (breathing 

 vitiated and confined air) ; these are, however, in reality, 

 more widely diffused, and, moreover, like hunger and thirst, 

 are connected with the need of the entire organism for a 

 greater or less quantity of oxygen. 



The lung may even be said to be much less sensitive t'.iau 

 the intestine ; we have seen that the latter, in pathological 

 cases, becomes extraordinarily susceptible to impressions; 

 the lung, on the contrary, in a similar case, gives no sign of 

 being diseased, unless the neighboring parts are affected, the 

 pleura, for instance (pleuritis)^ in general, however, the 

 maladies of the pulmonary surface occasion little pain, and 

 only give rise to a sensation of dyspnoea, a vague feeling of 

 discomfort, the seat of which is so little understood that 

 people commonly attribute it to the stomnch. 



The genito-urinary mucous, that we shall study later, most 

 usually presents only a dull sensation, always subjective, 

 ordinarily unlocalized, and in no wise informing us what 

 cause excites it. Properly speaking, there is no sensation 

 or sensibility in the kidney, testicles, or ovary. We will an- 

 alyze, farther on, the desire to urinate ; we shall find it wholly 

 similar to that for defecation, and shall see also that it is in no 

 less a, degree specially localized, and is composed of extrinsic 

 sensations, that we never perceive in those parts where they 

 are actually produced. The sexual desire may, on the one 

 hand, be compared with the desire to urinate, and, on the 

 other, with the desire to breathe, with that of hunger or of 

 thirst, for instance; it is a general desire, prod need under the 

 influence of a great number of circumstances, as much inter- 

 nal as external, and that we localize in the sexual organs^ 

 because we know the phenomena which take place in them, 

 and that are apt to calm the desire. 



The emission of spermatic fluid is accompanied with an 

 agreeable sensation that we refer to the terminal portion of 

 the canal of the urethra, but whose seat is but ill-defined, being 

 situated, like that of the desire to urinate, in the deeper 

 portion (prostatic region), because individuals whose glans 

 has been amputated refer their venereal sensations to the 

 navicular fossa of the urethra which they no longer possess. 



The womb has equally a mucous surface of dull, and 

 almost entirely reflex, sensibility, the most important of 



