68 HAND-BOOK OF PHYSIOLOGY. 



stratum of (salted) plasma. In order to cause this plasma to coagulate, 

 it is necessary to get rid of the salts by dialysis, or to dilute it with several 

 times its bulk of water. 



The antecedent of Fibrin. If plasma be saturated with solid 

 magnesium sulphate or sodium chloride, a white, sticky precipitate-, 

 called plasmine, is thrown down, after the removal of which, by nitration, 

 the plasma will not spontaneously coagulate. This plasmine is soluble 

 in dilute neutral saline solutions, and the solution of it speedily coagu- 

 lates, producing a clot composed of fibrin. From this we see that blood 

 plasma contains a substance without which it cannot coagulate, and a, 

 solution of which is spontaneously coagulable. This substance is very 

 soluble in dilute saline solutions, and is not, therefore, fibrin, which is 

 insoluble in these fluids. We are, therefore, led to the belief that plas- 

 mine produces or is converted into fibrin, when clotting of fluids contain- 

 ing it takes place. 



Nature of Plasmine. There seems distinct evidence that plasmine 

 is a compound body made up of two or more substances, and that it is 

 not mere soluble fibrin. This view is based upon the following observa- 

 tions: There exists in all the serous cavities of the body in health, e.g., 

 the pericardium, the peritoneum, and the pleura, a certain small amount 

 of transparent fluid, generally of a pale straw color, which in diseased 

 conditions may be greatly increased. It somewhat resembles serum in 

 appearance, but in reality differs from it, and is probably identical with 

 plasma. This serous fluid is not, as a rule, spontaneously coagulable, but 

 may be made to clot on the addition of serum, which is also a fluid which 

 has no tendency of itself to coagulate. The clot produced consists of 

 fibrin, and the clotting is identical with the clotting of plasma. From 

 the serous fluid (that from the inflamed tunica vaginalis testis or hydrocele 

 fluid is mostly used) we may obtain, by saturating it with solid mag- 

 nesium sulphate or sodium chloride, a white viscid substance as a precipi- 

 tate which is 'called fibrinogen, which may be separated by filtration, and 

 is then capable of being dissolved in water, as a certain amount of the 

 neutral salt is entangled with the precipitate sufficient to produce a dilute 

 saline solution in which it is soluble. This body belongs to the globulin 

 class of proteid substances. Its solution has no tendency to clot of itself. 

 Fibrinogen may also be obtained as a viscid precipitate from hydrocele 

 fluid by diluting it with water, and passing a brisk stream of carbon 

 dioxide gas through the solution. Now if serum be added to a solution 

 of fibrinogen, the mixture clots. 



From serum may be obtained another globulin very similar in proper- 

 ties to fibrinogen, if it be subjected to treatment similar to either of the 

 two methods by which fibrinogen is obtained from hydrocele fluid; this 

 substance is called par a globulin, and it may be separated by filtration ar.d 

 dissolved in a dilute saline solution in a manner similar to fibrinogen. 



