18 PROTEIN POISONS 



drates, but neither of these gives the reactions characteristic 

 of cellulose. One of these is certainly a constituent of the 

 nucleic acid group, having the same relation, or at least a 

 similar relation, to the other members of this group as 

 exists in the nucleins and nucleoproteins found in the 

 vegetable and animal world. Our studies together with 

 those of other investigators render it quite certain that 

 bacterial cellular substance yields the nuclein bases on 

 hydrolysis. The position of the second carbohydrate in 

 the molecular structure has not been determined with 

 certainty. It is thought possible that it is simply stored 

 in the cell as a reserve food supply; but that this is not 

 true is indicated by the fact that it cannot be removed by 

 simple solvents, and that its separation is secured only 

 after disruption of the molecular structure. We are inclined 

 to the opinion, subject to change as the result of more 

 exact knoAvledge, that the second carbohydrate group found 

 in at least some bacteria is an essential constituent of the 

 protein structure. Our work on the amino-acids, both 

 mono- and di-amino, makes it certain that the greater part 

 of the bacterial cell is made up of true proteins. We have 

 not only isolated and identified many of the amino-acids, 

 but we have shown that they exist in widely different 

 proportions in different species of bacteria, just as they do 

 in different proteins obtained from plants and animals. 

 While fats and waxes are found in relatively large amount 

 in certain bacteria, notably in bacillus tuberculosis, we 

 see no reason for concluding that they are essential con- 

 stituents of the living molecule. That they are specific 

 products of the life activities of certain bacteria we are 

 convinced, but we have seen no reason for believing that 

 they are essential constituents of the bacterial molecules. 

 We conclude that, chemically, bacteria, at least those 

 with which we have worked, are nucleoproteins or glyco- 

 nucleoproteins. While bacteria are morphologically simple 

 in structure and without differentiation in parts, chemically 

 they are complicated in structure, quite as much so as 

 many of the tissues of the higher plants and animals. The 



