1919] WOO—AMARANTHUS 319 



Equivalent in milligrams of NO3 8 



Milligrams of dry substance (25 cc.) used 107 



Percentage NO3 in soluble fractions Fi+Fj 8 



The percentage soluble fractions in whole samples 45 



Therefore percentage of NO3 calculated on whole sample. . 3 



Soil samples were taken at the same time that the green plants 

 were gathered. The nitrates were estimated by the colorimetric 

 method with phenoldisulphonic acid. The moisture in percentage 

 and nitrates in parts per million are shown in fig. i. 



On June 20 the samples from the manure pile and from the knoll 

 were taken for comparison. The nitrate content of the soil and 

 that in the plant were as follows: 



Knoll Manure pile 



sample sample 



NO3 in ppm in soU 300 29 



NO3 in percentage in plant (stem only) i . 71 i .45 



The high XO3 content in the soil of the knoll sample is probably 

 due to the fact that some one, perhaps the gardener, had disturbed 

 the soil by dragging his cultivator over it accidentally in cultivating 

 his plot near by. The second reason is the better drainage and 

 aeration in the knoll, and therefore better conditions for nitrifica- 

 tion; but the striking fact is that high nitrate content in the soil 

 did not bring about a proportional high nitrate content in the green 

 plant organs. The rate of absorption increases with the aging of 

 the plant; when the plants were about 25 days old, the nitrate 

 in the stem was only 1.71 per cent. Eighteen days later (July 8) 

 the nitrate content had risen to 8.58 per cent. During the same 

 period branches grew from o.i to 14 inches, and their nitrate 

 content rose to 12.50 per cent. This rapid increase in absorption 

 of nitrates may partially be explained by the increase in extent of 

 the absorbing roots from a radius of a few inches to about 2 ft. 



The nitrate content in the roots, stems, and leaves is given in 

 table II and is also shown in fig. i . The nitrate content of the roots 

 falls gradually from 1.85 per cent on June 3 to zero on June 20. 

 At the same time nitrates in the leaves fall from i .38 per cent to 

 zero, while in the stem there is a gradual increase. There must be 

 a definite reason for such differences. The differences may be due 



