There were, then, during the school year of 1909 and 1910, three distinct classes of children cared for by three distinct agencies--the classes for normal children in the low temperature rooms at the Graham School; anaemic children, with rest period and two lunches, in the Moseley and Hamline Open Window Rooms, and the Roof School for Tuberculous Children, with specially provided clothing, sleeping outfits, three meals a day and medical and nursing attendance, at the Mary Crane Nursery. The same condition existed throughout the following year--1910-11--with the addition of one Open Air School on the roof of the municipal bath building on Gault Court, given rent free by the City Health Department, and two Open Window Rooms for anaemic children in the Franklin School, all maintained by the Elizabeth McCormick Memorial Fund. In 1911 the Elizabeth McCormick Memorial Fund assumed the responsibility for all the open air school work carried on in the Chicago Public Schools, and began the standardization of methods which should be employed in the conduct of such schools. Through the initiative of the Elizabeth McCormick Memorial Fund the Chicago Open Air School work has been rapidly developed during 1912 and 1913, the program being along the line of additional roof schools for tuberculous children and an increasing number of open window rooms for anaemic children and children exposed to tuberculosis. In all this work the Elizabeth McCormick Memorial Fund has had the co-operation of the Board of Education, the Chicago Tuberculosis Institute and the Municipal Tuberculosis Sanitarium. The Board of Education has supplied teachers and furnished rooms wherever there has been a distinct demand for such a provision. During the past two years the Municipal Sanitarium has made appropriations aggregating $12,000 to pay the cost of food for these schools, in addition to furnishing the necessary nursing service. At the present time four Roof Schools and sixteen Open Window Rooms, with an enrollment of 500 pupils, are being maintained. For full information concerning the Chicago Open Air School movement, see "Open Air Crusaders," January, 1913, edition, published by the Elizabeth McCormick Memorial Fund, 315 Plymouth Court, Chicago; or write Mr. Sherman C. Kingsley, Director, Elizabeth McCormick Memorial Fund, for more recent developments. * * * * * Space will not permit a statement of the development of the Open Air Schools in other cities in the United States since this movement was started in 1908. It is, however, encouraging to note what has been accomplished and the comprehensive plans which are being made to further this great movement for the good of the future citizens of America. [Illustration] NOTES ON TUBERCULIN FOR NURSES VARIETIES OF TUBERCULIN--THEORIES OF TUBERCULIN REACTION--TUBERCULIN TESTS. By THEODORE B. SACHS, M. D.