44 PROTEIN POISONS 



dissolved to an opalescent fluid. This was heated in order 

 to insure sterilization, and injected into guinea-pigs, which 

 it killed within from six to twenty-four hours. One milli- 

 gram and even less of this undigested portion killed the 

 animals thus treated, but subsequent investigation showed 

 that the poisonous portion, when fully detached from the 

 other constituents of the protein molecule, kills in a few 

 minutes, and we concluded that the undigested part con- 

 sisted of several groups still attached, or, in other words, of 

 a larger and more complex group of which the poison is 

 only a part. The action of the proteolytic enzymes on 

 bacterial cells deserves a more thorough study than we 

 have given it. 



These preliminary studies quite convinced us so long ago 

 as 1901 that a typical colon bacillus, obtained from normal 

 human feces, does not elaborate in its cultures a soluble 

 poison, but that its cells do contain a highly active body. 

 Moreover, these studies indicate that the poison of the colon 

 bacillus exists in the essential proteins of the bacterial 

 cell, and that it cannot be isolated until these proteins are 

 broken up into their constituent parts. In other words, 

 the poison consists of one or more groups in the protein 

 molecule. Since the colon bacillus may grow in a medium 

 consisting solely of inorganic matter and a small amount 

 of some organic compound, as asparagin, its protein must 

 be formed synthetically, and its poison, as a constituent 

 of its protein, must be developed in the same way. One 

 is forced to the conclusion that the poison of this bacillus, 

 at least, does not result from the cleavage action of the 

 bacterial cell or its soluble ferments on the constituents 

 of the medium in which it grows, but that it is built up 

 synthetically, and is set free only when the cellular protein 

 is disrupted. In other words, the harmful action of bacillus 

 coli communis upon animals is not due directly to the 

 growth and multiplication of the organism in the animal 

 body, but to the breaking up of the bacterial protein and 

 the consequent liberation of its poisonous group. 



Subsequent and more extended research has shown that 



