458 



GENERATION. 



tervening between the ligature and the testicle. 

 It may be remarked, however, there are no 

 vesiculae seminales or reservoirs of semen in the 

 dog, and the result of such an experiment can 

 hardly with justice be applied to the human 

 species. On the other hand, it may be re- 

 marked that in man, while the testicle con- 

 tinually secretes a small quantity of semen, 

 and probably a larger quantity during venereal 

 excitement, it is obvious that the vesiculae 

 seminales serve as reservoirs in which the 

 seminal fluid accumulates ; for when in the 

 dead body fluids are thrown into the vas de- 

 ferens, they pass into the seminal vesicle of 

 the same side and distend it before issuing by 

 the orifice leading into the urethra. The se- 

 minal fluid after being secreted probably 

 follows in the living body the same course; 

 and from this circumstance as well as the 

 suddenness of emission, it is reasonable to 

 infer that the greater part of the ejaculated 

 semen, though formed in the testicles, comes 

 in man immediately from the seminal vesicles. 



The seminal vesicles we may suppose then 

 always to contain a certain quantity of seminal 

 fluid in the state of health. The accumu- 

 lation of semen in these vesicles relieves the 

 pressure which otherwise would distend too 

 much the secretory and excretory ducts of the 

 testicle, and the seminal vesicles are them- 

 selves relieved either by the sudden evacuation 

 of their contents from time to time, or by the 

 gradual absorption of the seminal fluid by the 

 absorbents or bloodvessels.* 



There is also reason to believe that the 

 mucous lining of the seminal vesicles secretes 

 a mucous fluid which is mixed with the 

 prolific product of the testicles. In some 

 animals, indeed, the vesiculae seminales open 

 separately from the vasa deferentia and dis- 

 charge by their excretory duct a fluid peculiar 

 to themselves. 



The impotence caused by castration or by 

 the ligature of the spermatic vessels suffici- 

 ently proves, that the testicles are the only 

 source of that part of the emitted fluid upon 

 which the fecundating power depends. 



The properties of the fluid supposed to be 

 derived from the prostatic body and Cowper's 

 glands have not been satisfactorily examined. 



The quantity of the seminal fluid emitted du- 

 ring sexual union varies in man from one to two 

 or three drachms. The seminal vesicles are not, 

 however, emptied at one emission, and, accord- 

 ing to Haller, when by repetition this comes to 

 be the case, two or three days are required in 

 man to fit them again for reproduction by a 

 new supply of fluid. 



Chemical properties of the spermatic fluid. 

 On cooling immediately after emission, the 

 seminal fluid jellies slightly, but in twenty or 

 twenty-five minutes it becomes more fluid 



* This absorption of semen into the general cir- 

 culation is conceived, not perhaps on very sufficient 

 grounds, to cause some of the peculiarities of the 

 male animal at the time of breeding ; to render 

 the flesh rank and unfit for eating j more readily 

 putrescent, &c. 



than at first, a change which does not appear 

 to depend upon the absorption of moisture from 

 the atmosphere, as its weight is diminished 

 rather than increased. 



The chemical properties of the seminal fluid 

 have been examined in man and several ani- 

 mals. It is generally considerably heavier 

 than water, has a peculiar odour, which in- 

 creases on keeping, is alcaline from the first, 

 and gives off ammonia when heated. Left at 

 rest for some time, it deposits crystals of phos- 

 phate of lime. 



According to the analysis of Vauquelin 

 human seminal uid consists of the following 

 ingredients : 



Water 90 



Animal mucus 6 



Free soda ^.... 1 



Phosphate of lime 3 



Peculiar animal principle 



100 



In the spermatic fluid of the horse, Las- 

 saigne has detected, besides the above-men- 

 tioned ingredients, the following substances : 



Muriates of potassa and soda, 



Phosphates of lime and magnesia, 



Peculiar animal matter called spermatine. 

 The milt of fishes, particularly that of the 

 carp, analysed by Fourcroy and Vauquelin, 

 contains 



An oily and saponaceous matter, 



Gelatine, 



Albumen, 



Muriate of ammonia, 



Phosphate of lime, 



of magnesia, 



of potassa, 



of soda. 



Phosphorus in such quantity as to emit 



light in the dark. 



The semen is fluid in almost all animals. 

 In some of the lower animals it is not so, but 

 granular and crumbling. In the greater num- 

 ber of animals the fluid is of a white milky 

 appearance and thinner consistence than in 

 man, presenting in fishes the appearance of an 

 emulsion of yolk of egg in milk. 



In respect to its mode of discharge there 

 are also many varieties dependent on the 

 structure of the generative organs. In the 

 lowest animals the testicle alone exists of the 

 genital organs, and the secretory apparatus 

 of this organ possesses a remarkably simple 

 structure, consisting in many of a number 

 of cceca or elongated follicles which pour 

 the product of their secretion into a com- 

 mon duct. In the cuttle-fish a very curious 

 modification exists in the mode of discharge 

 of the seminal fluid; it being inclosed in 

 small parcels in long-shaped transparent firm 

 cases, somewhat like small phials. These 

 cases are about three quarters of an inch in 

 length, and are formed in the course of the 

 vasa deferentia by an apparatus specially pro- 

 vided for the purpose: they are stopped at 

 one extremity, and at the other are closed by 



