348 VEHICLES OF CHEMICAL CORRELATION 



that it is almost invariably displayed only by the males of the hemo- 

 philic family, while the hereditary tendency to hemophilia is trans- 

 mitted by the females. This peculiar mode of inheritance is also 

 encountered in hereditary Color-blindness and in certain other instances 

 of inherited abnormality; it is designated Sex-linked Inheritance. 



We may therefore sum up the processes and substances concerned 

 in the coagulation of the blood as follows: 



The circulating plasma contains: 



Fibrinogen + Prothrombin + Calcium salts + Antithrombin 



Thrombin + Calcium salts Neutralized 



by kephalin. 



Hereafter unessential 



I 

 Fibrin. 



Howell believes that in addition to antithrombin properly so called, 

 which inhibits the action of thrombin upon fibrinogen, the circulating 

 plasma also contains an Antiprothrombin which inhibits the conversion 

 of prothrombin into thrombin by calcium salts and is, like anti- 

 thrombin, neutralized or inactivated by kephalin. 



In regard to the chemical nature of the substances which take part 

 in the coagulation of the blood, Fibrinogen is a globulin, being like 

 other globulins coagulable by half-saturation of its solution with 

 ammonium sulphate, but differing from the serum-globulins in being 

 also coagulable by half-saturation of its solutions with sodium chloride. 

 It is not known in what chemical respects Fibrin differs from fibrinogen, 

 but the results of Howell and others would seem to render very prob- 

 able the view that fibrin is a compound of fibrinogen and thrombin. 

 The jelly which is formed by the conversion of fibrinogen into fibrin 

 in the blood or in neutral or faintly acid salt solutions is of exceptional 

 interest because, as Schimmelbusch and Howell have shown, it consists 

 of an interlacing network of acicular crystals enclosing an interstitial 

 fluid (Fig. 19). If, however, fibrinogen be clotted in alkaline solution 

 the jelly, viewed under the microscope or ultra-microscope appears 

 to be structureless. The crystalline jellies display the characteristic 

 tendency of clotted blood to shrink in and express fluid, whereas the 

 structureless jellies do not. 



The source of the fibrinogen of the blood appears to be in the Liver, 

 since, as Whipple has shown, conditions associated with injury to or 

 insufficiency of the liver, such as Phosphorus or Chloroform poisoning 

 or hepatic cirrhosis lead to a marked diminution of the fibrinogen 

 content of the blood. 



