Because of the nature and variety of hydrographic conditions, the Gulf of Maine is a particularly favorable area for studies on the relation between marine plankton and the chemical constituents of the water. Data are given for phosphate, nitrate, nitrite and O in the water from various depths at 9 stations in the Gulf of Maine and on Georges Bank during early April. Curves show the correlation between these constituents, as well as with temp. O, nitrate and phosphate are in particularly close relation. Nitrate-N varied from 15 to 500 mg/m3; nitrite-N from 0 to 7.4 mg/m3; PO4 from 8 to 138 mg/m3. High values were obtained for nitrate, and especially for nitrite, from waters brought up with bottom mud. Nitrite was seldom found at the surface, but usually in maximal amounts at depths of 30-50 m. The relation of chemical analyses to the results of the phytoplankton and bacteriological studies made by other workers is discussed briefly.