Introduction In a former paper (8) by the writer, the effect of nitrogen on the chloroplast pigments has been especially indicated. The effect of nitrogen upon the growth of plants is perhaps greater than that of any of the other elements. VILLE (14) was perhaps the first to make any quantitative experiments on the effect of the various fertilizers upon the pigment content of plants. He has shown that nitrogen plays a role more important than that of any of the other elements tested. If the

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... of nitrogen was increased or diminished the color increased or diminished also. URBAN (13) found evidence of a correlation between the color of the leaves of beets and the nitrogen content, the darker leaves containing the most nitrogen and the lighter the least. Also, he apparently found a relation between the highest potassium content of the leaves and the greatest sugar content of the roots. In beets the dark colored leaves contained more potassium and less sodium than did the light colored leaves. In the leaves of ripening beets the potassium rapidly increases while the sodium decreases. A great difference in the chlorophyll content of alpine and of lowland plants was observed by HENRICI (2). She represented the amount of chlorophyll present in alpine plants as 100 per cent. and-found that lowland plants contained 230 per cent. and ravine plants 350 per cent. She makes no reference to the soil in which these grew but it is highly probable that the soil was a very important factor in the amount of chlorophyll which was found in the plants studied. Perhaps the first real experiments on the effect of chemical fertilizers