210 VAUGHAN— THE PROTEIN POISON. [April 19, 



that protein sensitization and bacterial immunity are one and the 

 same thing. In sensitization the animal dies on the second dose. In 

 -immunity the animal survives the second dose. Sensitization and 

 immunity are therefore apparently antipodal, but are in fact the 

 same thing. A man drinks water containing the typhoid bacillus, 

 and he does not develop typhoid fever that day, nor the next. He 

 passes through a period of incubation, which in typhoid fever is 

 somewhere about eight or ten days. During this time the typhoid 

 bacillus is multiplying in his body in great numbers, and in doing so 

 it is converting his proteins into typhoid proteins. Suddenly the 

 period of incubation stops and the disease begins to manifest itself. 

 The period of incubation stops when the body cells have become 

 sensitized to the typhoid protein, and begin to break it up. From 

 that time on the fight is between the living cells of the body with the 

 ferment which they pour out, and the bacilli. 



It occurred to us that if this theory be true we might demon- 

 strate it by repeated injections of small quantities of some protein 

 body, and determine what effect such injections might have upon 

 body temperature. In these experiments we have used egg-white 

 principally because we wanted to get away from cellular structure 

 and from the supposed influence of life. We wanted to take a dead 

 substance. Of course in doing so we recognized the fact that egg- 

 white does not grow and multiply in the body, and consequently we 

 must keep up the supply by repeated injections. I have published 

 several papers upon this, notably in the Zeitschrift fi'ir Iimnunitdts- 

 forschung, and therefore I am relieved from the necessity of going 

 into detail in this article. Suffice it to say that by varying the size 

 of the dose and the interval between the doses one can induce in the 

 lower animals any kind of fever that one wishes. One can place an 

 animal in a typhoid condition, and by repeated injections keep the 

 animal in this condition with a temperature identical with that of 

 typhoid fever for days and weeks. On the other hand, by more 

 frequent injections one can induce in a rabbit an acute, fatal fever, 

 terminating in a few hours ; or, by again varying the size of the 

 dose and the interval, one can secure at will the picture of remittent 

 or intermittent fever. Fever, therefore, results from the introduc- 



