PLASMINE, FIBRIN, METALBUMEN, SERINE, PEPTONES, ETC. 23 



the plasma may be separated by decantation ; to the plasma is added an excess of pul- 

 verized chloride of sodium, when a soft, pulpy substance is precipitated, which is plas- 

 mine. This substance, after desiccation, bears a proportion of about twenty-five pau- 

 per thousand of blood. It is soluble in from ten to twenty parts of water, when a por- 

 tion of it coagulates and may be removed by stirring with twigs or a bundle of broom- 

 corn, in the way in which fibrin is separated from the blood. The fibrin thus separated 

 is called by Denis concrete fibrin, and the substance which remains in solution, dissolved 

 fibrin. By most writers of the present day, the dissolved fibrin of Denis is called metal- 

 bumen, a name which we shall adopt. 



According to Denis, plasmine is a proximate principle of the blood, and, after extrac- 

 tion by the process just described, is decomposed into concrete fibrin and dissolved 

 fibrin, or metalbumen. Having removed the concrete fibrin from the solution of plas- 

 mine, the metalbumen is coagulated by the addition of sulphate of magnesia, which doec 

 not coagulate ordinary albumen. The proportion of dried metalbumen in the blood is 

 about twenty-two parts per thousand. The proportion of dried fibrin is about three 

 parts per thousand. 



After the extraction of plasmine from the blood, another coagulable substance re- 

 mains, which is called serine. This is coagulated by heat, the strong mineral acids, and 

 absolute alcohol, but is not coagulated by ether, which coagulates albumen of the white 

 of egg. Serine bears a close resemblance to ordinary albumen, but is stated to be much 

 more osmotic. Its proportion, desiccated, in the blood is about fifty-three parts per 

 thousand. 



We cannot admit the existence of new coagulable principles in the blood unless it be 

 shown that the processes by which they are extracted do not involve decomposition of 

 established proximate constituents. The processes just described do not seem to involve 

 artificial decomposition. It is perfectly proper, in analyzing the blood, to prevent spon- 

 taneous coagulation by the addition of the sulphate of soda, as this salt simply keeps 

 the blood lluid without apparently changing its organic constituents, and the plasmine is 

 simply precipitated by the chloride of sodium. It is evident, also, that the substance 

 called metalbumen, being coagulated by sulphate of magnesia, is not albumen, and 

 serine also presents some important points of difference from albumen. Admitting the 

 existence, then, of plasmine and serine, it is important to understand clearly the charac- 

 ters of these principles as compared with what were formerly called fibrin and albumen. 



Instead of fibrin and albumen in the blood, we now recognize two new principles, in 

 the natural condition of the circulating fluid, which are called plasmine and serine. The 

 substance known as fibrin is one of the products of decomposition of plasmine. Metal- 

 bumen and serine constitute what was formerly called albumen. Fibrin is not a proxi- 

 mate principle, but is formed in the spontaneous decomposition of plasmine. Metalbu- 

 men is the other product of decomposition of plasmine. The fibrin of arterial blood 

 has long been known to differ somewhat from the fibrin of venous blood, when the blood 

 has been allowed to coagulate spontaneously. Arterial fibrin is insoluble in a solution 

 of chloride of sodium which will dissolve the fibrin of venous blood. 



Peptones, etc. A certain quantity of nitrogenized matter, distinct from the principle* 

 just described, has been extracted from the blood, which is analogous to peptone or 

 albuminose. This is separated by coagulating the serum of the blood with hot acetic 

 acid and filtering, when the peptones pass through in the filtrate. These principles ;uv 

 probably derived from the food. Their proportion in the plasma is about four parts, 

 dried, per thousand, or twenty-eight parts before desiccation. 



A small quantity of coloring matter exists in the plasma. If we separate the corpus- 

 cles as completely as possible, the clear liquid still has a reddish-amber color. This col- 

 oring matter has never been isolated and studied. It is analogous to the coloring mat- 

 ters of the red corpuscles, the bile, and the urine. 



