Abstract
We owe to the kindness of Doctor Bordet a strain of B. coli with which he carried on his studies, a certain quantity of the corresponding lytic agent and a typical mucoid strain of his modified coli. With this material we have observed the following facts.
1. The inhibition produced by the lytic principle on the growth of B. coli is greatly influenced by the reaction of the medium: faint in a slightly acid (PH 6.8) or neutral (PH 7.0) or even slightly alkaline broth (PH 7.4), it is much stronger in a more alkaline medium (PH 8.0 or 8.5).
2. We have isolated from the original strain of B. coli two types of organisms: the one, Type S, 1 is sensitive to the lytic agent; the other, Type R, 1 is much more resistant. These types are distinguished also by other characteristics: type S grows quickly in artificial medium and is non-motile; type R grows móre slowly, is extremely motile, much less phagocytable and more virulent. Both types ferment carbohydrates, saccharose excepted; type R decolorizes neutral red, type S does not. Both types keep their individuality even after passage through a guinea pig.
3. The original lytic agent was found to be specific; it acted exclusively on the coli with which the guinea pigs had been injected. By allowing this original lytic principle to act on broth cultures of our two types of B. coli, we have obtained two new filtrates. The first, resulting from dissolution of the sensitive strain S, is specific as is the original filtrate. But with the second, obtained from the resistant strain R, Doctor Wollstein of the Rockefeller Institute has found a marked action on Shiga, on Flexner and on Hiss dysentery bacilli.
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