44 THE CIRCULATING LIQUIDS OF THE BODY 



venoms of some vipers (Martin). It is not known whether these 

 substances act on the blood-plates, leucocytes, or other cells, and 

 thus cause an increased production or an increased liberation of 

 one or more of the precursors of thrombin, or whether they take 

 part directly in its formation. But there is some evidence that 

 the venoms which favour coagulation do so in virtue of their con- 

 taining a kinase. On the other hand, cobra- venom prevents coagula- 

 tion by means of an antikinase that is, a substance which antago- 

 nizes the action of kinase, and so hinders the formation of thrombin. 

 It does not contain an antithrombin that is, a body which will 

 prevent the action of thrombin already formed (Mellanby). 



Relation of the Liver to Coagulation. It is not known with any 

 degree of certainty whether the thrombo-regulative processes are 

 especially associated with any particular organ. But there are 

 facts which suggest that the relations of the liver to the coagulation 

 of the blood are peculiarly close. Not only, as previously shown, 

 does it take an important share in the formation of fibrinogen, but 

 there is some evidence that it is closely related to the formation 

 of antithrombin. We have already mentioned that the injection 

 of commercial peptone, which consists chiefly of proteoses, into 

 the blood of dogs causes it to lose its coagulability. The effect 

 gradually passes away, till after some hours the original power of 

 coagulation is restored (p. 63) . The liver is known to be intimately 

 concerned in the production of this remarkable result, for if the 

 circulation through it be interrupted, the injection of proteose is 

 ineffective. Further, if a solution of proteose is artificially 

 circulated through an excised liver, a substance (perhaps an anti- 

 thrombin) is formed which is capable of suspending the coagula- 

 tion of blood outside of the body, a property which proteoses them- 

 selves do not possess, or possess only in slight degree. It is not 

 believed that the proteose is actually changed into this anticoagu- 

 lant substance, but rather that the liver cells produce it as a 

 ' reaction ' to the presence of the foreign substance, being perhaps 

 stimulated in some way by the circulating proteose. In part the 

 abnormally great alkalinity of the peptone blood, due to the excess 

 of alkali secreted by the liver, is responsible for its slow coagulation.) 

 Under certain conditions, some of which are known and others not, 

 the injection even of one or other of the purified proteoses causes 

 not retardation, but hastening, of coagulation ; and if this has been 

 the result of a first injection, a second is equally unsuccessful. It 

 is possible that by an effort of the organism to restore the normal 

 coagulability of the blood, on which its very existence depends, 

 substances which favour coagulation are produced, and that the 

 result of an injection of proteose is determined by the relative 

 amount of coagulant and anticoagulant secreted in a given time. 

 Protamins (products obtained from the ripe milt of certain fishes, 



