FURTHER STUDIES ON TYPHOIDIN

This paper records the results of further studies on typhoidin made since the publication of the original article of Gay and Force.

Since Gay and Force¹ have reviewed the work on the application of preparations of the typhoid organism to the skin which had been published previous to their article, we shall confine ourselves to a review of observations on typhoidin which have appeared since that date. The original typhoidin employed by Gay and Force consisted of a ten-day culture of a single strain of Bacillus typhosus on glycerin broth evaporated to one-tenth volume. On account of deterioration of the preparation in this form, Gay and Claypole² precipitated the original typhoidin with twenty volumes of alcohol, filtered, washed with absolute alcohol and ether, and then dried on porcelain plates over sulphuric acid in a vacuum. With a freshly prepared suspension of this typhoidin powder in phenolated saline, equivalent