I9I2-] VAUGHAN— THE PROTEIN POISON. 209 



upon the kind of protein injected and the species of animal. In 

 order to deal with this foreign material certain body cells develop 

 a specific proteolytic ferment, which splits up the protein injected, 

 and no other. The first dose is gradually split up, and consequently 

 produces no recognizable effect upon the animal. When a proper 

 interval of time is allowed to elapse before the second injection, 

 this new ferment, in the form of a zymogen is stored up in certain 

 cells of the body, and when the second injection of the same protein 

 is made this zymogen is activated, and converted into a ferment 

 which splits up the injected protein with great rapidity, setting free 

 the same poison which we obtained by splitting up proteins with 

 sodium hydroxid in absolute alcohol. This explanation of the 

 phenomena of protein sensitization was published by Wheeler and 

 myself in 1907. Recently it has been confirmed in France by Nicolle 

 and Abt, and in Germany by Friedberger. It is true that Fried- 

 berger does not fully give us credit for this work. He says that 

 we suggested this explanation, and he has demonstrated it. It is 

 unfortunately true that much of the scientific work done in Amer- 

 ica must go to Germany and be approved before it is accepted by 

 other Americans. This is due to our lack of confidence in ourselves 

 and in one another. The German has so long been accustomed to 

 stamp his products as " made in Germany," that much of our scien- 

 tific work comes back with this stamp upon it. However, it is not 

 my purpose to complain about this matter. My European confreres 

 have given me, on the whole, fair credit for work done along this 

 line. 



More recently we have attempted to use the knowledge which 

 we have gained in the study of the protein poison in the explanation 

 of many of the phenomena of immunity and of disease. The essen- 

 tial difference between egg-white and the typhoid bacillus is that the 

 former is a non-labile, dead protein, while the bacillus is a labile, 

 living protein. If egg-white could grow and multiply after being 

 introduced under the skin, or into the blood of an animal, it would 

 be just as dangerous to prick a finger with a needle moistened with 

 this relatively harmless, bland protein as it would to inoculate one- 

 self with the anthrax bacillus. As early as 1907 Wheeler and I held 



