Dec. 15, 1925 
Nitrogen Metabolism in Etiolated Corn Seedlings 
1161 
germination showed 5.47 per cent (Nos. 23 and 24), and after 8 days 
it rose to 8.50 per cent (Nos. 25 and 26). In the period from the 
eighth to the fifteenth day the acid-amide nitrogen remained almost 
constant (showing a slight diminution). The same regularities hold 
good when the latter is calculated to the water-soluble nitrogen or 
to the oven-dried seedlings. 
The reverse, however, holds good for the humin nitrogen. Thus, 
while the ungerminated seed (Nos. 15 and 16) showed 21.70 per cent, 
it gradually decreased to 19.51, 12.27, and 10.52 per cent (Nos. 1 
to 6) after 2, 4, and 8 days, respectively. The same is true of the 
uspulun-treated seed, which after 4 da^s of germination had 8.57 
per cent (No. 7), but after 8 days had but 6.45 per cent (Nos. 9 and 
10), calculated on the water-soluble nitrogen. In the period from 
the eighth to the fifteenth day the humin nitrogen showed a slight 
increase. 
With regard to the amino nitrogen, it will be seen that from 9.52 
per cent in the ungerminated seed (Nos. 15 and 16) it rose rather 
rapidly to 20.83 and 27.82 per cent after 2 and 4 days, respectively. 
Equally, the uspulun-treated seed showed an increase to 28.29, 
29.55, 30.97, and 31.52 per cent after 4, 8, 11, and 15 days (Nos. 7 
to 14), respectively, calculated on the basis of the water-soluble 
nitrogen. About the same relationship holds good when the amino 
nitrogen is calculated on either the total nitrogen or the oven-dried 
seedlings. 
The figures for the peptide nitrogen show a reverse relationship. 
Thus, while the ungerminated seed (Nos. 15 and 16) had 35.03 
per cent, it diminished to 34.06 and 26.77 per cent after 2 and 4 days, 
respectively, and in the case of the uspulun-treated seed it changed to 
34.52, 27.52, 26.17, and 20.19 after 4, 8, 11, and 15 days, respectively, 
when calculated to the water-soluble nitrogen. The fact that the 
amino nitrogen rose at the same time that the peptide nitrogep 
diminished seems to indicate that the former increased at the expense 
of the latter. 
The residual nitrogen, representing the difference between the total 
soluble nitrogen and the sum of the various nitrogenous compounds 
estimated, is rather fluctuating, as would be expected.* 
In Nos. 33 to 48 the results expressed in percentage of the oven- 
dried seedlings were given for the sake of completeness. These have 
not been recalculated to the original oven-dried seed. 
The results in Table V are based upon the aqueous extracts (of 
the seedlings) which were successively treated with acetic and tannic 
acids. Although this treatment removes the proteins, it may not 
remove proteoses and peptones quantitatively (I, p. 609). If such 
be the case, the increase in amino nitrogen, on hydrolysis, as re¬ 
ported previously, could be due not only to the presence of poly- 
* peptides but also to that of proteoses and peptones. Hence, it 
seemed necessary, quantitatively, to remove any proteoses and 
peptones present prior to the hydrolysis. This was accomplished 
with the aid of phosphotungstic acid by the following method: 
On distilling off the ammonia, corresponding to the nitrogen of 
acid amides, the filtrate and washings from the magnesium oxide 
residue were concentrated on the water bath and made up to 100 c. c. 
On cooling, the solution was treated with 5 gms. of sulphuric acid and 
