302 THE BLOOD. 



stituents by means of centrifugal force yields abundant fibrin when it is not 

 separated from a substance which precipitates on cooling. This substance, 

 which WOOLDRIDGE has called A-fibrinogen, seems to all appearances to be a 

 nucleoproteid, which, according to the unanimous view of several investigators, 

 originates from the form-elements of the blood, either the blood-plates or the 

 leucocytes, and the generally accepted view as to the great importance of the 

 form-elements in the coagulation of the blood is not really contrary to WOOL- 

 DKIDGE'S experiments. 



There is great diversity of opinion in regard to those bodies which 

 are eliminated from the form-elements of the blood before and during 

 coagulation. 



According to ALEX. SCHMIDT the leucocytes, like all cells, contain 

 two chief groups of constituents, one of which accelerates coagulation, 

 while the other retards or hinders it. The first may be extracted from the 

 cells by alcohol, while the other cannot be extracted. Blood-plasma 

 contains only traces of thrombin, according to SCHMIDT, but does con- 

 tain its antecedent, prothrombin. The bodies which accelerate coagu- 

 lation are neither thrombin nor prothrombin, but they act in this wise 

 in that they split off thrombin from the prothrombin. On this account 

 they are called zymoplastic substances by ALEX. SCHMIDT. The nature 

 of these bodies is unknown, and SCHMIDT has given no opinion as to 

 their relation to the lime salts, which have been found to have zymoplastic 

 activity by other investigators. 



The constituents of the cells which hinder coagulation and which 

 are insoluble in alcohol-ether are compound proteins, and have been 

 called cytoglobin and preglobulin by SCHMIDT. The retarding action 

 of these bodies may be suppressed by the addition of zymoplastic sub- 

 stances, and the yield of fibrin on coagulation in this case is much greater 

 than in the absence of the compound protein retarding coagulation. 

 This last supplies the material from which the fibrin is produced. The 

 process is, according to SCHMIDT, as follows: The preglobulin first splits, 

 yielding serglobulin, then from this the fibrinogen is derived, and from 

 this latter the fibrin is produced. The object of the thrombin is two- 

 fold. The thrombin first splits the fibinogen from the paraglobulin and 

 then converts the fibrinogen into fibrin. The assumption that fibrinogen 

 can be split from paraglobulin has not sufficient foundation and is even 

 improbable. 



According to SCHMIDT the retarding action of the cells is prominent 

 during life, while the accelerating action is especially pronounced out- 

 side of the body or by coming in contact with foreign bodies. The paren- 

 chymous masses of the organs and tissues, through which the blood flows 

 in the capillaries, are those cell-masses which serve to keep the blood 

 fluid during life. 



LILIENFELD has given further proof as to the occurrence in the form- 



