EMPLOYMENT OF BLOOD SERUM 271 



natural antibodies are increased by specific immunization. The use of 

 normal serum in non-specific therapy probably increases those non- 

 specific factors of defense such as fever, serum enzymes, etc., that 

 have already been discussed. In hemophilia, purpura hemorrhagica, 

 melena neonatorum and similar hemorrhagic diseases there is a disturb- 

 ance of proper balance of those constituents of the blood and tissues 

 which provide for coagulation of the blood. Hypotheses differ as to 

 the exact mechanism of the process of coagulation, but fundamentally 

 it seems necessary to have an equilibrium of prothrombin and anti- 

 thrombin. This balance may be upset by an excess of antithrombin, 

 by a deficiency in prothrombin, fibrinogen, calcium salts or other ele- 

 ments. The interaction of prothrombin, thrombokinase (or thrombo- 

 plastin) and calcium salts results in the formation of thrombin. 

 Thrombin and fibrinogen interact to form fibrin, the essential element 

 of a clot. Blood serum is rich in prothrombin and if a hemorrhagic 

 disease be due to prothrombin deficiency, serum treatment is likely to 

 be beneficial. If, on the other hand, the disease be due to an excess 

 of antithrombin the introduction of prothrombin has little value. 

 Similarly hemorrhagic disease with low fibrinogen content is not bene- 

 fited by serum treatment. Whipple has found decrease of fibrinogen 

 in advanced cirrhosis of the liver with hemorrhage, excess of antithrom- 

 bin in aplastic anemia and leucemia and deficiency of prothrombin 

 in melena neonatorum. Duke holds that the lack of prothrombin 

 is due to a deficiency in the number of platelets, whereas Minot 

 and Lee believe that in hemophilia, at least, the slow clotting is due 

 to a hereditary defect in the platelets which renders them less avail- 

 able for the process of coagulation. Various studies have given different 

 results as to the changes found in the elements concerned in clotting. 

 Whipple points out that if the phenomenon is studied in the individual 

 case rational therapy may be applied. In melena neonatorum the ad- 

 ministration of blood serum often gives brilliant results. In other 

 hemorrhagic diseases the results are somewhat more variable. If 

 hemorrhage has been severe and anemia is marked, the double purpose 

 of favoring clotting and replacing lost blood may be served by trans- 

 fusion from a suitable and properly-tested donor. The more direct 

 the transfusion the less likelihood is there of alteration of the blood 

 due to beginning clotting and the greater is the probability of con- 

 tributing substances to replace or augment those which may be deficient 

 in the patient's blood. 



