70 SOURCE OF THE FIBRINOGENOUS SUBSTANCES. 



calcium is precipitated by alkali-oxalate this prevents coagulation, 

 although it is true that the presence of a large amount of ferment in the 

 blood is capable of neutralizing the influence of the calcium. Fibrin- 

 ogen and fibrin contain equal amounts of calcium. Probably the 

 action of the calcium bears some relation to -the formation of the fibrin- 

 ferment, for the plasma contains a substance that exerts a marked 

 coagulative effect after addition of calcium-salts. 



According to Kossel and Lilienfeld the leukonuclein contained in the nuclei 

 of the leukocytes, and the nucleinic acid resulting from its decomposition, accelerate 

 coagulation. 



If coagulation has taken place in the plasma of the blood, all of the 

 fibrinogenous material in the serum is utilized for the formation of 

 fibrin. On the other hand, fibrin-ferment will still be present in the 

 serum in sufficient amount. Therefore, if blood-serum be added to a 

 fluid containing fibrinogen, as, for instance, hydrocele-fluid, coagulation 

 will at once take place anew. 



SOURCE OF THE FIBRINOGENOUS SUBSTANCES. 



Alexander Schmidt has found that both fibrin-factors are formed 

 from the destruction of leukocytes. In the circulating blood of man 

 and of mammals, the fibrinogenous substance is already dissolved in 

 the plasma as a soluble product of the physiologic involution-processes 

 of the white cells. The circulating blood, however, contains a much 

 larger number of leukocytes than was previously believed. As soon as 

 the blood is shed, large numbers of white blood-corpuscles are dissolved 

 according to Alex. Schmidt 71.7 per cent, in the horse. The decom- 

 position-products dissolve in the blood-plasma, and as a result the fibrin- 

 ferment develops, to a certain extent as a cadaveric product, causing 

 the separation of fibrin. Accordingly the fibrin-ferment does not preexist 

 within the uninjured corpuscles. Also the so-called transitional forms 

 between colorless cells and erythrocytes in mammalian blood furnish 

 the fibrin-factors as a result of their destruction, which takes place 

 immediately after escape of the blood ; likewise perhaps also the blood- 

 plates. The ferment develops with the escape of the blood, and its 

 formation reaches the maximum during the process of coagulation 

 itself. 



The influence of adhesion in favoring coagulation depends upon the fact 

 that as a result the blood-corpuscles are caused to give up a portion of their 

 contents phosphoric acid and alkaline phosphates to the plasma, to combine 

 with salts of calcium and magnesium present principally in the plasma. If the 

 calcium be precipitated from the blood by means of oxalic acid i gram of 

 potassium oxalate to i liter of blood coagulation no longer takes place. If, how- 

 ever, calcium chlorid be again added to this mixture coagulation will result. 



In the blood of amphibia and birds it is the red blood-corpuscles that after 

 escape undergo destruction in large numbers and furnish the fibrin-forming mate- 

 rials. In the blood of these animals Alex. Schmidt convinced^ himself at the same 

 time that also the fibrinogenous substance was originally a constituent of the blood- 

 corpuscles. 



It is thus clear that as soon as the fibrin-factors pass into solution in 

 consequence of dissolution of the blood-corpuscles the separation of 

 fibrin must take place through the combination of the two substances. 



If considerable amounts of leukocytes are introduced into the circulation of 

 an animal they are quickly dissolved in large numbers in the blood, so that even 



