THE LIMITS OF SERUM-THERAPY. 755 



toxic serum, the active principle of which is trypsin, to a blood- 

 stream already overburdened with trypsin that we can hope to 

 overcome typhoid fever and kindred disorders in which fibrin- 

 ogen is inadequately formed. If, in addition, we realize that 

 an active febrile process (the organism's main protective re- 

 source against bacilli and their toxins) indicates that the ad- 

 renal system is in full activity, and that the plasma contains 

 an ample proportion of oxidizing substance besides trypsin, it 

 seems but logical to conclude that: 



In febrile diseases attended with hypoleucocytosis and in 

 which an excess of trypsin is found to exist (by the Widal or other 

 tests) a serum rich in FIBRINOGEN should be administered. 



Indeed, Eichardson 90 found, in his observations in forty- 

 one typhoid patients at different stages of the disease, that "in 

 the stage of convalescence or falling temperature, the normal 

 element returns apparently to the blood, and a corresponding 

 destruction of bacilli takes place." He also remarks almost 

 prophetically, if our views are sound, though he ascribes the 

 hypothetical effects, in accord with Ehrlich and others, to the 

 "immune substance" (our oxidizing substance): "We can, there- 

 fore, hazard a guess why serum-therapy in typhoid fever and 

 allied diseases has made so little progress. We have been giving 

 a serum loaded with immune element with which the patient 

 was perhaps already surfeited, and we have neglected to give 

 the element that was necessary to make active powerful agen- 

 cies already present in the patient's blood. Apparently, there- 

 fore, we should give to most of our typhoids normal serum." 

 We have seen, by Wassermann's experiments, that fresh ox- 

 serum sufficed to save infected guinea-pigs. 



Can we use fresh serum in human beings? The cytolytic 

 action of the serum of one species when introduced into the 

 blood-stream of animals of another species is well known. In 

 the light of our analysis this is accounted for by the fact that 

 the blood introduced too suddenly augments the proportion of 

 trypsin in the host's blood (trypsin being practically limited, 

 we have seen, to the leucocytes during health), and, finding the 

 fibrinogen and oxidizing substance necessary to greatly increase 

 its dissociating energy, it attacks the red corpuscles as it would 



*> Richardson: Loc. cit., p. 199. 



48 



