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THE PHENOMENA OF INFECTION 473 



The most striking peculiarity mentioned in connection 

 with the above idiosyncrasies is the rapidity with which 

 the symptoms of poisoning develop after the introduction 

 of the attending cause within the alimentary tract. As 

 has been mentioned, these individual peculiarities are 

 possibly best explained by the supposition that the individual 

 has become sensitized to certain specific proteins, the sensi- 

 tization arising from the fact that the particular protein 

 has gained entrance into the body through the intestinal 

 mucosa in an unchanged state. When this occurs a foreign 

 protein is present in the tissues and fluids of the body, and 

 to counteract the abnormal condition thus produced certain 

 body cells are called on to develop a proteolytic ferment 

 which will have for its function the cleavage of the particular 

 protein present in any given case. This ferment, once 

 formed, is stored up in certain cells as a zymogen for future 

 use. The same protein cleavage then occurs as normally 

 takes place within the intestinal canal, with the important 

 difference that the toxic substances formed are liberated 

 within the body itself and consequently are capable of 

 exerting their harmful action. That these ferments are 

 not present in the body in inexhaustible amount is shown 

 experimentally by the fact that animals which have recovered 

 from the effects of sensitization following a second injection 

 of egg albumen are not subsequently sensitive to this 

 protein until after the lapse of several days. This is un- 

 doubtedly due to the fact that the ferment has been largely 

 used up in bringing about the cleavage of this particular 

 protein and time must be allowed for the body cells to 

 produce an additional amount. In other words, it is possible 

 in a susceptible individual to destroy their susceptibility 

 with regard to any particular protein through an exhaustion 

 of the special ferment present in their body. This is well 

 illustrated clinically by the following example: A woman 

 who was fond of strawberries, but developed an intensely 

 disagreeable urticaria after each indulgence, was accustomed 

 to eat this fruit two or three times during the season. 

 Finally, being firmly convinced that the rash was simply a 



