748 
Journal of Agricultural Research 
Vol. V, No. 16 
Nitrogen supply. —That the organism was influenced by the kind 
and amount of the nitrogen supplied seemed evident from the results of 
experiments with standard media, such as beef broth and beef agar, as 
well as the results already reported for pea broth. 
A number of preliminary experiments of the same type as those re¬ 
ported under carbohydrates were performed at the same time, and these 
indicated that the various nitrates influenced pycnidium formation. But 
these results were not altogether consistent. The following experiment 
(see Table XXII) with filter paper and tap water plus various chemi¬ 
cals, and the similar series in which distilled water was used, may be 
cited as typical. 
Table XXII .—Effect of quality of food: Test with various nitrates 
[Time, i month] 
Chemical. 
Present as— 
Distilled water. 
Tap water. 
1 
Pycnidia. 
Growth. 
Pycnidia. 
Growth, 
Calcium nitrate. 
Potassium nitrate. 
Calcium acid phosphate (Ca(H 2 - 
M/lOO . 
Ml IOO _ 
Ml200, Ml 100 
20-30 
50-100 
3 °-S° 
+ + 
+ + + 
+ + + 
20-50 
50-IOO 
IOO+ 
+++ 
+++ 
++ 
P 0 4 ) 2 ) + calcium nitrate. 
Potassium acid phosphate + 
Mj 100 each. . 
+ + + 
IOO+ 
+ 
potassium nitrate. 
Filter paper. 
Check. 
9-20 
4 - . 
7-12 
+ 
From this experiment it could not be determined beyond question 
that the nitrate ion was the potent factor in this increase in pycnidia 
formation, but the corresponding behavior of both the calcium and the 
potassium nitrate indicated that this was extremely likely. The increase 
in pycnidium production upon the addition of both a phosphate and a 
nitrate to this carbohydrate medium is significant. 
Since the nature of the carbon assimilation might greatly influence the 
nitrogen assimilation, experiments with these two compounds can 
hardly be separated. In the following experiment an attempt was made 
to test various classes of carbon-furnishing compounds with various 
nitrogen sources. In this experiment the mineral solution mentioned in 
the preceding section was used. The stock solution contained monobasic 
potassium phosphate as M/ioo, sodium carbonate as M/ioo, and magne¬ 
sium sulphate as M/ 500. To different portions of this, malic acid, glycerol, 
and maltose were added, respectively, so that each chemical was present 
at M/100 concentration. A fourth series was prepared as a check, and 
in this cones of filter paper furnished the carbon supply (S. & S. 605). 
The various solutions were put into series of preparation dishes, 5 c. c. per 
dish. To these dishes the nitrogen compounds to be tested were added 
from a clean pipette 1 drop (1/20 c. c.) of the proper solution (stock 
solutions were made up M/50, except peptone, which was 2 per cent) to 
