CHEMICAL EXAMINATION OF THE BLOOD. 325 



while not denying the existence of the ferment, regards it as a de- 

 composition-product which is formed during the coagulation of the 

 blood. According to his ideas, it cannot very well be concerned in 

 this process, and he assumes that the coagulation of the blood is 

 normally referable to the acid radicle of the nucleohiston, which, as 

 we have seen, is present in the nuclei of the leucocytes in large 

 amounts. 



The leuconuclein, however, does not cause the coagulation of the 

 blood at once, but first effects the decomposition of fibrinogen with 

 the formation of thrombosin and an albuinose-like body, which may 

 be a derivative of Hammarsten's fibrinoglobulin. The thrombosin 

 is soluble in dilute alkalies. Upon the addition of a soluble calcium 

 salt, however, such solutions coagulate, and the thrombosin is thus 

 transformed into the insoluble fibrin. Fibrin, according to this 

 theory, is thus a calcium compound of thrombosin. 



The active principle of the leuconuclein is unquestionably its 

 nucleinic acid radicle, and, as a matter of fact, the same changes 

 can be brought about by using this directly. This explains the 

 observation which has been repeatedly made, that the coagulation 

 of albuminous fluids which are not spontaneously coagulable can also 

 be effected by the addition of almost any cellular formation, such 

 as yeast cells, various bacteria and moulds, spermatozoa and pro- 

 tozoa, etc. i. e., bodies which all contain fairly large amounts of 

 nucleins. It is to be noted, moreover, that the intensity of action 

 of these various substances is intimately dependent upon the amount 

 of nuclein present, and we accordingly find that of all the cellular 

 elements of the body the spermatozoa are the most active. While 

 this portion of Lilienfeld's theory is practically unassailable, some 

 doubt has been raised as to the existence of his soluble thrombosin, 

 and Hammarsten thus states that the thrombosin is no decomposi- 

 tion-product of fibrinogen, but fibrinogen itself which has been pre- 

 cipitated with nucleinic acid. He has shown, moreover, that the 

 formation of fibrin can take place in the absence of calcium salts, 

 providing that a sufficient amount of the fibrin ferment is present. 

 If we are to accept Lilienfeld's theory then, we may imagine that 

 through the influence of the soluble calcium salt the nucleohiston is 

 decomposed, and that the leuconuclein is thus enabled to exercise its 

 special activity. Future researches, however, will be necessary to 

 settle this question definitely, and to determine whether the coagu- 

 lation of the blood is normally referable only to the action of 

 nucleins, and whether the fibrin ferment is in reality a product of 

 coagulation. 



The question, why the blood does not coagulate within the vessels 

 of the body where fibrinogenic material is available, and where leuco- 

 cytes no doubt undergo degeneration, has been variously answered. 

 On the one hand, it is stated that the integrity of the endothelial 

 lining is here of prime importance, and that coagulation will occur 

 whenever this is impaired. As a matter of fact, we find that coagu- 



