tend to depress It. The blood -which distends the corpora 

 flosa of the penis, and the corpus spongiosum of the urethra and glans, 

 which is itself the expanded extremity of the urethra, does not stagnate in 

 their cells, only there is a greater quantity of blood in them than usual; the 

 irritation increasing, in a remarkable manner, the action of the arteries. 

 Erection, always proportioned to the degree of the stimulus, ceases, 

 when the cause of irritation no longer acts on the penis; in the same 

 manner that an inflammatory tumour is discussed, when the cause is re- 

 moved*. In this voluptuous dilatation, the urethra is brought into a state 

 of erection, being put on the stretch by the penis which is elongated, its 

 curves are straightened, the irritation is propagated from the external to 

 the internal parts, to the vesiculse seminales and the testicles. These 

 swell, and their secretion is increased, as they receive a gentle degree of 

 motion from the action of the scrotum, which becomes wrinkled and 

 draws them up towards the abdomen, and by the action of the cremaster 

 muscle, whose expansion formsbetween the tunica vaginalis and the dar- 

 tos, what has been improperly called the tunica erythroidea ; they empty 

 themselvess with the greater ease along the vasa deferentia, which de- 

 crease in length, as the testicles rise, and which participate in the con- 

 cussion affecting these organs. 



The concussions of the cremaster on the testicle, or on the vassa defe- 

 rentia, promote, in so important a manner, the secretion and excretion of 

 the semen, that this little muscle is fonnd in animals whose testicles never 

 leave the abdomen, but remain within that cavity on the sides of the lum- 

 bar region, as was observed by Hunter in the hedge-hog and the ram. 

 This fact of comparative anatomy shows that the cremaster is of use, not 

 merely in suspending the testicles, as its name indicates, since in the ani- 

 mals above-mentioned they return into the abdomen towards the organ 

 on which they are to act. 



When irritation is carried to a certain length, it acts on the vesicu- 

 lae seminales, and these on the fluid which fills their cavity, and they 

 expel it, by the spasmodic contraction of their membranous parietes, as- 

 sisted, in this excretion, by the levatores ani. (CCI.) The prostrate 

 gland and the mucus glands of the urethra furnish a viscid substance, cal- 

 culated to promote the evacuation of the seminal fluid, which is emitted 

 in jets, more or less rapid. 



CCIV. The human semen is never emitted in a state of purity, that 

 is, such as it is prepared by the testicles : it is even conjectured, that the 

 mucous fluid of the vesiculae seminales forms the greatest part of it. It 

 is this mucous which eunuchs emit in considerable quantity. The fluid 

 secreted by the prostrate gland and by the mucus glands of the urethra, 

 affect it, likewise, by uniting with it. 



On being received into a vessel, it exhales a peculiar smell like that of 

 the pollen of a great number of plants, for example, of the chesnnt-tree. 

 It consists of two parts, the one thick and in clots, while the other is vis- 

 cid, white, and more fluid. The proportion of the fluid to the semi-con- 

 crete part is greater, in proportion as the person is weaker, and as the 

 emission of semen is more frequently repeated. It soon liquifies, by 

 losing part of its weight, which always exceeds that of water in which it 



* The animal heat is somewhat augmented, during erection, as in inflammation. The 

 temperature of the blossoms of tire arum rises several degrees above that of the atmos- 

 phere, at the moment of impregnation. 



