Many thanks for your letter of August 24 and the culture of L-type [ . . . ] L-21. When I have tested it, I will let you
know my findings.
Under seperate corr I send the strain W 0459, 37-38 mutated[?] from blood, of L typhin[?] type 2 and for my experiments on
the xylose-dulcitol relationship. I do not think this phenomenon is due to a [ . . . ] shift mutation in which the capacity
to ferment one sugar is accompanied by the loss on another, and vice versa. The phase which does not ferment xylose grown
on dulcitol medium as on the medium without dulcitol which the xylose-fermenting phase specifically
inhibited by dulcitol. Perhaps this may be due to a fermentation of dulcitol without acid production by xylose of the original
weakly fermenting form. I have
shown cases of simultaneously acquired fermentation of more than one sugar, but no cases of shift-mutation you ask about.