332 PROTEIN POISONS 



or soon after anaphylactic shock to show measurable proteo- 

 clastic effect is due to the accumulation of the cleavage 

 products in the blood. That all the phenomena of anaphyl- 

 axis are not due to cleavage ferments in the blood-serum 

 must be evident to all who have followed us thus far. The 

 work of Pfeiffer and Mita, that of Zunz, our own, and that 

 of others agree in showing that the property of splitting up 

 the sensitizing protein, in measurable quantity, at least, 

 disappears from the blood-serum of the sensitized animal 

 long before the anaphylactic state disappears. When a 

 guinea-pig is sensitized to horse serum, the blood-serum of 

 this animal looses the power to split up horse serum in vitro 

 in appreciable amount after from twenty to sixty days, but 

 the animal remains sensitive to horse serum for at least two 

 years, as shown by Rosenau and Anderson, and probably 

 so long as the animal lives. We must therefore agree with 

 Zunz that the increased proteoclastic property of the blood- 

 ferum of the sensitized animal is not sufficient to account 

 sor all the phenomena of sensitization. Our theory of sensi- 

 tization takes this into account. We hold that sensitization 

 develops in certain body cells a new function that of 

 elaborating a new specific, proteoclastic ferment. The 

 duration of this new function varies with the sensitizing 

 protein and with the cells in which it is developed. In a 

 given cell this function must be limited by the life of the 

 cell. We do not know just what cells develop this new func- 

 tion, but we do know that the animal may remain in a 

 sensitized state long after the blood-serum fails to show any 

 cleavage action on the sensitizing protein in vitro. It may 

 be that the specific ferment present in the blood-serum of 

 recently sensitized animals comes from the white corpusc'es, 

 or it may come in part, or altogether; from fixed cells. It 

 seems justifiable to conclude that the ferment which manifests 

 its action in animals long after it is absent from the blood 

 must come from fixed cells, and that these are stimulated to 

 elaborate this ferment only when the specific protein is 

 brought into contact with them, probably only when they 

 are permeated by the specific protein. All the facts which 



