30 POISONOUS PROTEINS 



one-third the nitrogen passes into solution when 

 the substance is treated with these solvents. 



POISONOUS ACTION. We have found all the 

 bacterial cellular proteins poisonous. Our ear- 

 lier work was done with the colon cell substance. 

 Since all of these bodies are insoluble in water 

 or salt-solution, it has been necessary to admin- 

 ister them in suspension. Early studies demon- 

 strated the following facts: (1) The poison is 

 contained within the bacterial cell and does not 

 under ordinary conditions diffuse into the cul- 

 ture medium.* It is true that old cultures may 

 contain soluble poisons, but these result from 

 autolysis. (2) The poison is not extracted from 

 the cellular substance by water, saline solution, 

 alcohol or ether, either at ordinary temperature 

 or at the boiling point. (3) Heating, even to 

 140 in the autoclave does not destroy the 

 poison. (4) Dilute (0.5 per cent) solutions of 

 caustic alkali disrupt the cellular substance 

 slowly and imperfectly. Stronger (2 per cent) 

 solutions break up the cell substance and render 

 the poisonous fraction soluble. (5) Boiling 

 with dilute mineral acid (to 1 per cent) has but 

 little effect. 



At first we were much puzzled by the fact that 

 smaller doses killed while larger ones failed to 



*It is understood that we are speaking of cellular poisons and not of 

 bacterial toxins. 



