224 MANTJAL OF PHYSIOLOGY. 



The solution prepared from the hydrocele fluid causes blood 

 serum to coagulate ; that prepared from the blood serum causes 

 the hydrocele fluid to coagulate; and when mixed together the 

 mixture of the two solutions coagulates ; while the serum and 

 hydrocele fluid from which the substances have been removed no 

 longer have the power of exciting coagulation in each other or 

 in like fluids. Here, then, are brought to light two materials : 

 one, which may be obtained in considerable quantity from serum 

 after coagulation, is called serum globulin or paraglobulin, the 

 other, occurring in serous fluids, is named fibrinogen. Both of 

 these substances are present in the dying plasma of the blood 

 prior to coagulation. They can be obtained both together from 

 the plasma (when either of the precautions already mentioned, 

 viz., the application of cold, or the addition of neutral salt, has 

 been taken to prevent the formation of fibrin) if the plasma be 

 treated with sodium chloride to saturation. This precipitates a 

 substance which readily dissolves if water be added to weaken 

 the salt solution, and after some time the solution undergoes 

 spontaneous coagulation, while the plasma from which it has been 

 made has lost that power. This plasmin (Denis), no doubt, is made 

 of different globulins, chiefly serum globulin and fibrinogen, and 

 contains in itself all the necessary " factors " of fibrin formation, 

 but is not at all identical with fibrin, since it readily dissolves 

 in weak saline solutions, like the class of proteids called globu- 

 lins, while fibrin is quite insoluble in such solutions. 



In plasma removed from its normal relationships, then, both 

 serum globulin and fibrinogen exist ; but the former in far greater 

 quantity than the latter, since the serum, after the blood clot is 

 formed, contains no more fibrinogen, while the serum globulin or 

 paraglobulin makes up nearly half the entire solids of the remain- 

 ing serum. 



In preparing fibrinogen and paraglobulin (or, as he called the 

 latter, fibrinoplastin) , Schmidt found that the more carefully they 

 were made, the weaker and more uncertain their action as fibrin 

 factors became; and, finally, he made solutions which, when added 

 together, did not produce coagulation, but which, when added to 

 less pure solutions, give good firm clots. From this he suspected 



