SEMEN. 499 



CHAPTER XIII. 



OF SEMEN. 



THE liquor secreted in the testes of males, and destined for 

 the impregnation of the female, is known by the name of semen. 

 The human semen and the milt of fresh-water fishes alone have 

 hitherto been subjected to a chemical examination. Nothing is 

 known concerning the semen of other animals. Vauquelin pub- 

 lished an analysis of human semen in 1791.* Jordan made some 

 experiments on it in ISOl.-f- Dr John also examined it, though 

 I have never seen the paper which he published on the subject 

 Berzelius likewise has subjected semen to a chemical examina- 

 tion, J 



I. Semen, when newly ejected, is evidently a mixture of two dif- 

 ferent substances. The one, fluid and milky, which is supposed 

 to be secreted by the prostate gland ; the other, which is consi- 

 dered as the secretion of the testes or the true semen, is a thick 

 mucilaginous substance, in which numerous white filaments may 

 be discovered. These filaments constitute a peculiar animal 

 principle, which has been distinguished by the name of spermatin. 



Semen has a slight but unpleasant smell, an acrid irritating 

 taste, and its specific gravity is higher than that of water. When 

 rubbed in a mortar, it becomes frothy, and of the consistence of 

 pomatum, in consequence of its enveloping a great number of 

 air-bubbles. It changes syrup of violets to green, from the un- 

 combined soda which it contains. 



As the liquid cools, the mucilaginous part becomes thready, 

 and acquires greater consistency, but in about twenty minutes 

 after its emission, the whole becomes liquid. This liquefaction is 

 not owing to the absorption of moisture, for it loses instead of 

 gaining weight ; nor to the action of the air, for it takes place 

 equally in vacuo. 



Semen is insoluble in water before this liquefaction, but after- 

 wards it dissolves readily in it. When alcohol or chlorine is ad- 

 ded to this solution, white flocks separate. Alkalies readily dis- 

 solve the semen, and it is soluble in concentrated sulphuric acid, 



* Ann. de Chim. ix. 64. f Crell's Annalen, 1801, i. 461. 



\ Traite de Chimie, vii. 558. 



