BACTERIAL CELLULAR SUBSTANCE 45 



the stability of the protein molecule varies within wide 

 limits, and that the facts learned in the study of the special 

 strain of the colon bacillus do not hold strictly true in 

 every particular with all proteins. This was expected, and 

 we hoped to obtain from these preliminary studies nothing 

 more than certain standards by which our findings in more 

 extended studies might be measured. With some strains 

 of the colon, and in many more of the typhoid bacillus, 

 we have obtained evidence of the presence of soluble poisons 

 in old cultures. For the most part at least these come from 

 autolysis of the bacterial cell. This is a subject to which 

 we shall return in recording the development of these 

 researches. 



The findings in our early studies quite naturally developed 

 several inquiries, some of which may be formulated as 

 follows: If the protein of the colon bacillus contains a 

 poisonous group, may not the proteins of other pathogenic 

 bacteria contain similar groups, and if the proteins of patho- 

 genic bacteria contain poisonous groups, why should not the 

 proteins of non-pathogenic bacteria possess like constituents. 

 If bacterial proteins contain poisonous groups, why should 

 not other proteins, such as those of vegetable and animal 

 origin, contain like groups, and if all proteins possess in 

 their structure, poisonous bodies, how is it that the animal 

 world, including man, lives so largely on proteins? Attempts 

 to solve these questions have taken our time and energy, 

 and given us much pleasure. The results of these labors 

 constitute the principal record of this volume. 



Marshall and Gelston 1 made an exhaustive study of the 

 toxicity of the cellular substance of the colon bacillus. At 

 first they employed material coarsely ground in a porcelain 

 mortar. This was suspended in water, boiled to insure 

 complete sterilization, and then injected intra-abdominally 

 in guinea-pigs. Up to 1 part of poison to 40,000 parts of 

 body weight all animals treated in this way died. When 

 the proportion was reduced to 1 to 50,000 and less, none of 



1 Trans. Assoc. Amer. Phys., 1902, xvii, 298. 



