During the summer of 1906, notwithstanding the completion of, and the satisfactory results obtained from, the Washington filtration works, it was found, contrary to the general expectation, that there was no diminution in the prevalence of typhoid fever. Owing to the limited force of inspectors under the health officers and the entire absence of a bacteriologic laboratory under his control, no extended investigation into the causation of this condition could be conducted. Consequently, in June, 1906, the District Commissioners requested the aid of the Bureau of Public Health and Marine-Hospital Service toward solving this problem. The work of the bureau covered the conditions that existed within the limits of the District. Very early in the course of the investigations attention was forcibly drawn to the milk supply. A summary of work done was submitted to the District Commissioners in March last. Ten per cent. of the cases of typhoid fever