358 THE SECRETIONS: 



roughly, becomes opalescent, and resembles a long thread : it 

 is now incapacitated from returning to a state of solution like 

 fresh semen, but remains, on being dried, fibrous, snow-white, 

 and opaque. It gradually softens in water, but even at the 

 boiling point only a very small portion dissolves in that fluid; 

 it swells, however, like mucus. If the water in which it has 

 been boiled is evaporated, a white matter remains, which is 

 partly soluble in cold, partly in boiling water, and the solution 

 is freely precipitable by tannic acid. That portion of the semen, 

 after coagulation by alcohol, which is not soluble in boiling 

 water, will also resist the action of dilute solution of potash at 

 a moderate temperature; it will, however, dissolve on being 

 heated with a concentrated solution of caustic potash, and it 

 cannot be again precipitated from this solution by acetic acid. 

 With concentrated sulphuric acid it forms a yellow fluid, with- 

 out the application of heat ; on the addition of water it is pre- 

 cipitated with a white colour, and the precipitate is not soluble 

 in an excess of water. 



With acetic acid the coagulum becomes gelatinous and trans- 

 parent ; on being diluted and warmed it dissolves, but does not 

 form a perfectly clear fluid : this is only rendered turbid by fer- 

 rocyanide of potassium, is not precipitated by bichloride of 

 mercury or carbonate of ammonia, but by tannic acid is thrown 

 down in light floccules, which continue for a long time in 

 suspension. 



From these researches Berzelius concludes that the semen 

 contains a peculiar matter which may be obtained in two sepa- 

 rate states depending upon whether it be projected into water 

 or alcohol. When coagulated by alcohol it has an external re- 

 semblance to fibrin, and, moreover, like that substance, it can 

 be precipitated from its acetic-acid solution by ferrocyanide of 

 potassium : on the other hand, it differs from it in its solubility 

 in nitric acid, and in its power of resisting the soluble action of 

 a cold solution of potash. 



On heating the residue of the semen it becomes yellow, 

 emits an odour of burnt horn, gives off a considerable quantity 

 of ammonia, and leaves a carbonaceous mass which is not 

 easy of incineration, and contains carbonate of soda, chloride 

 of sodium, and phosphates of lime and magnesia. Vauquelin 

 assigns the following composition to the seminal fluid. 



