SEMP.N. See PHYSIOLOGY Semen is secreted in the testes of male animals; but when it is ejected it is composed of two substances ; the one is fluid and milky, and the other of a thick mucilagi nous consistence, in which appear a great number of white, silky filaments, especi ally if it be agitated in cold water It has a disagreeable odour, and an acrid irritat ing taste. The specific gravity varies con siderably, but is always greater than that of water When it is rubbed in a mortar, it froths up, and acquires the consistence of pomatum from the air with which it mixes It converts the flowers of violets to a green colour, and it precipitates the calcareous and metallic salts, which shows that it contains an uncombined alkali. The thick part of the semen, as it cools, becomes transparent, and assumes ' a greater degree of consistence ; hut it af terwards becomes entirely liquid, even without absorbing moisture from air If semen he exposed to the air after it has become liquid at the temperature of sixty degrees, it becomes covered with a trans parent pellicle, and at the end of three or four days deposits fine transparent crys tals of a line in length, crossing each other like radii from a centre. When they are magnified, they appear to be four-sided prisms, terminated by long four-sided pyramids. When semen is ex posed to a warm air, in considerable quan tity, it is decomposed ; it assumes the colour of the yolk of egg, and becomes acid, either by absorbing the oxygen from the atmosphere, or by a different combi nation and arrangement of its own consti tuent principles. Heat accelerates the
liquefaction of semen ; and when it has undergone this change, it is no longer susceptible of coagulation. It is deCom posed by the application of strong heat. Water is first separated ; it then blackens, swells up, and emits yellow fumes, having an empyreumatic, ammoniacal colour. A light coal remains behind, which burns readily to white ashes.
The acids readily dissolve semen, and this solution is not decomposed by the alkalies; nor indeed is the alkaline solu tion of semen decomposed by the acids. Wine, cider, and urine, also dissolve se men, but it is in consequence of the acid which is combined with these liquids. The crystals which form in semen by spontaneous evaporation in the open air, and which are entangled in the viscid matter, may be separated by adding water.
These crystals have neither smell nor taste They melt under the blow-pipe into a white opaque globule. which is surrounded with a yellowish flame This salt is insoluble in water, and is not acted on by the alkalies ; but is soluble in the mineral acids without effervescence, from which solutions lime water, the alkalies, and oxalic acid, throw down a precipitate. The component parts of semen are found to be Water 90 Mucilage 6 Soda 1 Phosphate of lime . 3 100