140 PHYSIOLOGY CHAP. 



perish, how is it that thrombosis does not occur in circulating 

 blood, since both fibrin ferment and coagulative nucleic substances 

 must be poured into the plasma on the disintegration of the 

 corpuscles ? 



This question has not at present been adequately considered. 



Fano, on the strength of certain ingenious experiments, 

 suggested that peptonised blood does not coagulate because it 

 contains an anti-coagulating substance of uncertain nature, which 

 comes, not from the formed elements of the blood, but from the 

 other tissues seeing that the addition of peptone to freshly-drawn 

 blood does not inhibit its coagulation. A. Schmidt, in pursuance 

 of this theory, subsequently extracted his cytoylobulin, which has 

 a pure anti-coagulative action (and is probably identical with 

 historic), from the lymph glands and other tissues as above stated. 

 On the ground of many experiments, he maintains that the liquid 

 state of circulating blood must be regarded as a function- of the 

 living cells of the fixed tissues, with which the blood is in 

 continual exchange. These receive the nutrient matters from the 

 blood, and return to it the products of their metabolism, including 

 the globulins (the mother substance of fibrin) and cytoglobulin, 

 which obstructs the coagulative action of the ferment that con- 

 stantly diffuses in the blood owing to the disintegration of the 

 nuclei of the leucocytes. When the blood is extracted from the 

 vessels, cytoglobulin no longer pours in, while thrombin, owing to 

 the rapid alteration of the leucocytes, is abundantly present, and 

 coagulation takes place. 



The latest experiments of Lilienfeld show the ease with which 

 nucleohistone, when introduced into the circulation, breaks up by a 

 process of which we are wholly ignorant, into its two components, 

 the coagulating leuconuclein, and the anti-coagulating historic, 

 which last is found in a free state in blood drawn off immediately 

 after the injection, and according to Wright is present in urine also. 

 Lilienfeld, however, makes no definite suggestion as to why, under 

 normal conditions of circulating blood, the anti-coagulative action 

 of the histone always outweighs the coagulative action both of the 

 ' nucleic substances and of the ferment, even when the latter is 

 present in great quantities in the plasma, as occurs with the 

 innocuous transfusion of defibrinated blood or of simple serum. 



In regard to this and other phenomena, which call for more 

 adequate explanation, we cannot at present feel satisfied with the 

 work that has been done, or the theories proposed, in reference to 

 blood coagulation. 



The latest attempts to discover why the blood does not clot 

 within the vessels, admit the presence of an anti-thrombin, or 

 substance which neutralises the action of the small amount of 

 thrombin present in normal blood. 



According to the observations of Nolf and others, the incoagul- 



