LIBERATION oF OrGANIC Marrer By Roots oF GROWING PLANTS 9 
The potatoes were grown in turf and sand in the greenhouse. Applica- 
tions of fertilizer were made so that plant nutrients would not be deficient. 
Harvests were made on June 12, June 30, August 7, and September 14. 
The plant parts were divided into foliage and tubers. The figures for 
weight of nitrogen show that there was a constant decrease of this con- 
stituent in the foliage after the first harvest, altho there was a constant 
increase in the weight of the tubers. The total plant, however, had its 
greatest amount of nitrogen on August 7, with a decrease of 6.46 per cent 
thirty-eight days later. 
Pots containing 5.3 kilograms of dry earth received fertilizers to stimulate 
growth of plants and to furnish an abundant supply of nutrients. The 
seeding of mustard was done on May 7, and subsequently all pots con- 
tained six plants. The experiment was run in duplicate. The mustard 
was harvested, first, on the appearance of the first pods, second, when the 
formation of seed was complete, and third, at maturity. Analysis of the 
total plant only was made. The total nitrogen was greatest when the 
formation of seed was complete. The loss at the third harvest was about 
10 per cent of the total nitrogen. 
With the intention of verifying the results obtained by Wilfarth, Romer, 
and Wimmer, André (1912) cut barley at five different stages of growth 
from equal areas of land and analyzed the dry harvest. The cuttings were 
made (1) when the heads began to show, (2) when the barley was in bloom, 
(3) when seed began to form, (4) at the mature stage, and (5) beyond the 
ripe stage. The figures for total nitrogen show 7.023 grams at the first 
stage, 8.693 at blooming, 10.422 when the fruit was forming, 12.589 at 
maturity, and 10.360 at the last harvest. 
The object of an experiment by Ramsay and Robertson (1918) was to 
determine the relative proportions of each of the principal nutrient elements 
contained in the plant at various stages of growth. They grew potatoes 
in soil in boxes containing about 130 pounds of well-drained and fertilized 
soil. Approximately the same weight of seed was put in each box. The 
first harvest was gathered on January 29, thirty-three days after brairding, 
the second on February 25, the third on March 26, and the last on April 
30. At the first three harvests complete recovery of tops and roots was 
|made. The last harvest was more difficult and about 30 per cent of the 
roots were lost. Cropping, harvesting, and analyzing were done in dupli- 
eate in each case. The total nitrogen contained in a 20-ton crop of 
