Dec. 15, 1925 
Nitrogen Metabolism in Etiolated Corn Seedlings 1153 
Beginning with the eighth day and continuing to the fifteenth 
there was a slight increase in the protein nitrogen. There would 
seem to be an effort on the part of the etiolated seedlings to synthe¬ 
size proteins. For this process they needed energy, which, in the 
absence of light, they derived from breaking down the reserve 
materials of the seed, such as the starch. 
The figures for the nonprotein nitrogen, found by direct estima¬ 
tion, quite naturally stand in reverse ratio to the protein nitrogen. 
Thus, the ungerminated seed (Nos. 28 and 29) with the highest pro¬ 
tein nitrogen (95.68 per cent) has the lowest nonprotein nitrogen 
(4.31 per cent). Equally, the five-day uspulun-treated seedlings 
(Nos. 20 and 21) with the lowest protein nitrogen (54.52 per cent) 
have the highest nonprotein nitrogen (48.01 per cent). 
The percentage of total nitrogen, it will be noticed, increases some¬ 
what with the duration of germination, when calculated on the basis 
of the oven-dried seedlings. In this connection it should be remem¬ 
bered that the whole .of the seedlings, including the seed, was taken 
into the work. Therefore, strictly speaking, the total nitrogen of the 
seedlings should be equal to the total nitrogen of the seed, provided 
the weight of the seedlings (including the unutilized seed) at any time 
would be equal to that of the ungerminated seed. Actually, however, 
the weight of the former decreases more and more as germination 
progresses, because the seedlings, in the absence of light, derive the 
energy necessary for growth, respiration, and other vital activities 
from oxidation or cleavage of the stored-up materials. If only non- 
nitrogenous compounds such as starch were utilized for the creation of 
energy, then the total nitrogen calculated on the basis of the oven- 
dried seedlings should, with the progress of germination, gradually 
become greater than the nitrogen proportion in the ungerminated 
seed. However, the growing seedlings can and do obtain the nec¬ 
essary energy also by the cleavage and further degradation of nitroge¬ 
nous compounds such as proteins, as is evident from the observation 
on proteolytic anzymes reported subsequently. Since this decom¬ 
position may be accompanied by loss of nitrogen, it has the tendency 
to decrease the proportion of nitrogen in the seedlings. It is for these 
reasons that the total nitrogen was calculated to the oven-dried seed¬ 
lings as well as to the seed. The circumstance that the total nitrogen 
calculated on the seedlings is higher than in the ungerminated seed 
is an indication that the growing seedlings derive the necessary 
energy chiefly at the expense of the nonnitrogenous compounds, 
such as starch. This is also corroborated by the observation that the 
aqueous extracts of the seedlings contained less starch the further the 
germination progressed. 
In order to recalculate the nitrogen found directly in the seedlings 
to the oven-dried seed, experiments were made to ascertain the 
change of weight of the seed on germination. Each of several per¬ 
forated copper trays was covered with absorbent paper towels and 
divided into equal parallel sections. On each of these there were 
planted 10 uniform-looking corn kernels, the weight of which was 
accurately determined. On covering the seed with absorbent paper, 
the whole was thoroughly sprinkled with water and allowed to ger¬ 
minate in a dark room under exactly the same conditions as described 
above. After the expiration of 2, 4, and more days, all of the seed- 
