I9I2-] VAUGHAN— THE PROTEIN POISON. 207 



its capability of producing a poison, because all bacterial cells con- 

 tain a poison. Whether a germ is pathogenic to a given species of 

 animal or not depends upon its capability of growing and multiply- 

 ing in that animal's body. 



Next we looked for this poison in certain animal proteins, such 

 as the white of egg, the proteins of blood serum, the casein of milk, 

 etc. In all of these the same or a like poison was found by the same 

 method. Later we tested vegetable proteins, such as the gluten of 

 flour, the zein of corn meal, the edestin of hemp seed, etc. Up to 

 the present time we have examined more than thirty proteins of 

 bacterial, animal and vegetable origin, and in all of these the same 

 poisonous group has been detected. 



It has long been suspected, and indeed I may say, known, that 

 the protein molecule contains a poisonous group. At first it was 

 supposed that the diverse proteins which man takes in his food are 

 but slightly altered in the alimentary canal, and before absorption. 

 It is now known that this is not true, and that in the healthy man 

 all proteins are broken down into amino acids by the ferments of 

 the alimentary canal, and that these amino acids are, either during 

 absorption or directly thereafter, resynthesized so as to form the 

 proteins which are characteristic of man's body. The precipitin 

 test has demonstrated that every species of animal has its own spe- 

 cific protein bodies. Every albuminous molecule contains a poison- 

 ous group. Peptones injected into the blood act as poisons; there- 

 fore the peptone group contains a poisonous molecule, and it is this 

 poisonous molecule in the peptone group which we have succeeded 

 in partially isolating. The symptoms induced by this protein poison 

 are marked and characteristic. They divide themselves into three 

 distinct groups. Soon after the injection of a minimum fatal dose 

 in one of the lower animals there is evidence of peripheral irrita- 

 tion. This is shown by the fact that the animal becomes restless 

 and attempts to scratch itself, not only the part adjacent to the 

 point of injection, but every portion of its body which it can reach. 

 This is known as the stage of peripheral irritation. In man it is 

 characterized by itching and by an erythematous eruption which 

 begins about the place of injection, and rapidly spreads over the 



