PARENTERAL DIGESTION 69 



specific ferment and the poison formed may 

 come from the proteins of the blood, but if all 

 this be true, and the weight of evidence today 

 is in this direction, the anaphylactic reaction 

 remains specific. We have only transferred the 

 problem of specificity from the development 

 of a specific enzyme to the specific uncovering 

 of a nonspecific enzyme. It remains true that 

 an animal sensitized to one protein is not sen- 

 sitized to other and unlike proteins. 



I have said that the theory of the uncovering 

 of a general protease in anaphylactic shock has 

 much in its favor. The blood seems to be a 

 fluid in which ferments and antiferments are 

 nicely and delicately balanced and a slight dis- 

 turbance in this equilibrium leads to marked 

 effect. We have obtained from one gram of 

 casein enough of the protein poison to kill 800 

 guinea-pigs when injected intravenously. That 

 casein, the chief protein constituent of the food 

 of all mammalian young, should be found to 

 contain a body so highly poisonous when intro- 

 duced intravenously is certainly a surprising 

 thing. However, the surprise does not disap- 

 pear when we go further and find that a simi- 

 lar poison may be obtained not only from all the 

 proteins we eat but also from those that make 

 up the tissue of our own bodies. Indeed, every 



