It is of the greatest importance in tests of the sanitary quality of water and milk supplies that organisms which specifically cause infectious diseases through such sources shall be subject to methods of rapid and definite isolation. Up to the present time this has been a matter of great difficulty and uncertainty owing to the fact that the disease germs which occur in water and especially in milk are intermingled with, and greatly outnumbered by, other intestinal germs and many species of common so-called air and water bacteria. CHEMICAL PRECIPITATION AND AGGLUTINATION. Many methods have been employed in isolating or attempting to isolate the typhoid bacillus from water. Processes involving chemical precipitation have been studied by Vallet,' Schuder," Ficker,' Mtiller,s Willson," Nietor,? and Ditthorn and Gildemeister,? the latter using ox bile as an enrichment medium after chemical precipitation. Agglutination has also been used in enrichment methods for the isolation of B. typhosus by Adami and Chopin," Klotz." Shipilewski,xo and Altschuler. II INDICATOR DYES AND DIFFERENTIAL CHEMICALS.

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All drawings should be made with India ink, preferably on tracing cloth. If co6rdinate paper is used, blue must be chosen, as all other colors blur on reduction. The larger squares, curves, etc., which will show in the finished cut, are to be inked in. Blue prints and photostats are not suitable for reproduction. Lettering should be even, and large enough to reproduce well when the drawing is reduced to the width of a single column of THIS JOURNAL, or less frequently to double column width. Authors are requested to follow the SOCIETY'S spellings on drawings, e. g., sulfur, per cent, gage, etc.

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