In December, 1917, the Medical Advisory Board was organized. This included all the men who were carrying on experimental work of a medical nature. This board had as its object the correlation of all medical work; new work was outlined and attempts were made to secure the co-operation of scientific men throughout the country. The following groups of workers assisted in this effort: At Yale, Underhill studied therapy, turning his animals over to Winternitz for pathological study. Henderson was specially interested in the physiology of aviation. At the American University Marshall carried on pharmacological research, specially as regards mustard gas, the toxicology being covered by Loevenhart. A pathological laboratory was also started, under Winternitz, where many valuable studies were made.[14] At Cleveland Sollmann was busy with mustard gas and protective agents. Pearce, working in co-operation with Dr. Geer of the Goodrich Rubber Company, perfected the Goodrich Lakeside Mask. His study was very valuable as concerning the physiology of the gas mask. At Ann Arbor Warthin and Weller[15] were studying the physiology and pathology of mustard gas. Wells, Amberg, Helmholz and Austin of the Otho Sprague Memorial Institute were interested in protective clothing, while at Madison, Eyster, Loevenhart and Meek were engaged in a study of the chronic effect of long exposures to low concentrations, and later expanded their work to protective ointments and certain problems in pathology. [Footnote 14: See the Pathology of War Gas Poisoning, 1920, Yale Press.] [Footnote 15: See Medical Aspects of Mustard Gas Poisoning, 1919, C. O. Mosby Co.] In the spring of 1918 many of these men were commissioned into the Gas Defense Service of the Sanitary Corps, and were later transferred to the Chemical Warfare Service as the Medical Division, with Colonel W. J. Lyster, M.C., in charge. One of the most important functions of this Division was the daily testing of a large number of compounds for toxicity, lachrymatory or vesicant properties. The accuracy of these tests might and probably did save a large amount of unnecessary experimental work on the part of the Research Division. These tests are described in a later chapter. Very interesting and likewise valuable was the study of mustard gas by Marshall, Lynch and Smith. They were able to work out the mechanism of its action and the varying degrees of susceptibility in individuals (see page 171). Another interesting point was the fact that in the case of certain gases there is a cumulative effect. With superpalite and mustard gas the lethal concentration (that concentration which is fatal after a given exposure) is lower on longer exposures. On the other hand there is no cumulative effect with hydrocyanic acid. Whether the action is cumulative or not depends on the rate at which the system destroys or eliminates the poison. LIAISON OFFICERS