294 
Journal of Agricultural Research 
Vol. XXXI, No. 3 
reagent and filtered again; 15 c. c. of this last filtrate was diluted to 
50 c. c. in a Nessler tube and tested for nitrite with the sulphanilic 
acid mixture (2, p . 23 ). The extract from diseased material gave a 
very strong p>ink, showing presence of nitrites, whereas a similar 
procedure with healthy material and with blanks gave no reaction. 
■ To determine total hydrolyzable nitrogen, samples of 4 gms. each 
of the dried powder in 200 c. c. of 20 per cent hydrochloric acid were 
boiled for 9 hours in 500 c. c. Kjeldahl flasks under a reflux condenser. 
The “humin” nitrogen was then filtered off and washed. The 
filtrate and washings were then made up to liter. Total hydro¬ 
lyzable nitrogen was determined by Kieldahlizing 250 c. c. portions 
of the filtrate. 
Nitrogen Distribution in the Hyrdolyzed Material 
The filter paper bearing the “humin” nitrogen precipitate was 
returned to the Kjeldahl flasks used in refluxing, and the digestion 
and distillation carried out by the Kjeldahl-Gunning method. The 
nitrogen recovered was called ‘‘humin.” 
Acid-amide nitrogen was determined by using aliquot portions of 
the hydrolyzed material which were made slightly alkaline with 
strong alkali, and the acid-amide nitrogen forming ammonia, together 
with the ammonia nitrogen present, was aerated off as in the ammonia 
nitrogen determinations. 
Total amino nitrogen was determined by use of the Van Slyke 
micromethod. To avoid the interference of the presence of ammonia 
and amido nitrogen, the aerated solutions from the acid-amide 
nitrogen determinations after neutralization with sulphuric acid were 
used. . 
The protein nitrogen was determined by the method of Stutzer 
in which 1 gm. samples of the dry celery powder were treated as 
described in the work with the Cercospora material. 
The figures for nonprotein nitrogen were obtained by computation. 
The results of the analyses by the above described methods are 
given in Tables III and IV. 
Table III. — Average nitrogen distribution in healthy celery leases and in leaves 
affected with Septoria leaf spot (Septoria apii) 1 
[Total nitrogen expressed in percentage of oven-dried leaves: Healthy, 5.10 per cent; diseased, 4.38 per cent. 
Nitrogen distribution expressed in terms of total nitrogen] 
Diseased 
Healthy 
Nitric nitrogen,___ 
5.7 
5.8 
Ammonia nitrogen_________ 
1.3 
0.3 
(*) 
Nitrogen of nitrites________ 
.(*) 
Total hydrolyzable nitrogen___ 
84.9 
88.8 
Acid amide__ 
11.8 
13.5 
“Humin”. _ 
10.9 
9.6 
Total amino nitrogen__________ 
43.5 
47.1 
Protein nitrogen __ ___ 
72.6 
67.8 
Nonprotein nitrogen ______ 
27.1 
32.1 
i For data from which these averages are computed see Table IV. 3 present. 3 Absent. 
