Jan. 17,1916 
Plenodomus fuscomaculans 
753 
Tabus XXV .—Effect of quality of food: Complex media compared with synthetic solution 
Medium. 
Start. 
Reaction. 
One 
month. 
Growth character. 
Aerial form. 
Pycnidia. 
Time. 
Prune-juice agar (broth 
from 75 gr.). 
Glucose agar 6 (glucose 3 
per cent; peptone 1 per 
cent). 
Corn-meal agar (Shear)... 
+8 
Standard agar.... 
Standard gelatin. 
Filter paper.. 
+10 
+15 
+20 
± 
Parsnip plug. 
Carrot plug. 
Pea broth (2 seeds in 10 
c. c.). 
Com broth (2 grains in 
10 c. c.). 
+8 
+8 
Beans (2 seeds in 10 c. c.). 
Bananas (autoclaved)... 
Rice plus 5Xwater. 
Oats (2 grains in 10 c. c.). 
Raulin solution. 
Synthetic solution: 
Potassium acid phos¬ 
phate, Ml TOO. 
Magnesium sulphate, 
M/500. 
Maltose, Mfioo . 
Asparagin, Mfsoo .... 
+ 5 
+30 
+30 
+8 
“S 
—5 
± 
+5 
± 
+20 
+ 5 
Strong white mycelium, 
becoming greenish. 
Medium reddened. 
White, restricted growth 
becoming red-brown; 
oidia. 
Weak growth of myce¬ 
lium, mostly sub¬ 
merged; no mat. 
Strong growth, white, 
forming mat. 
Strong growth, white, 
gelatin slowly liquefied. 
Scant amount creeping 
from point of inocula¬ 
tion, becoming greenish 
black, paper not discol¬ 
ored. 
Strong, quickly covering 
plug, which shrivels. 
Color white, then tawny 
As above, color greenish 
at close. 
Strong, forming tough 
mat, which becomes 
submerged; white. 
Scant to medium amount, 
submerged, forming a 
film, otherwise no aerial 
growth, blackening at 
time of fruiting. 
As in peas. 
Strong, covering slice, 
reddish brown when 
old. 
Strong, covering grains, 
which blacken after a 
month; white myce¬ 
lium becoming gray- 
green. 
Weak, submerged growth 
forming film; blackens 
in a month. 
Strong white, becoming 
tawny. 
Good white growth, sub¬ 
merged, forming film 
on surface, on which 
pycnidia form; myce¬ 
lium blackens just be¬ 
fore fruiting. 
Strong tufted. 
Prominent... 
Scant, if any. 
Scant, if any. 
Fair amount. 
Tufts. 
Tufts. 
Scant. 
Strong. 
Strong tufted 
+++« 
o 
+ + 
o 
o 
++ 
+++ 
+++ 
o 
++++ 
3 weeks. 
4 weeks. 
1-3 weeks. 
4 weeks. 
4 weeks. 
15 - 20 
days. 
Slowl 
Strong tufted 
+++++ 
4 weeks. 
4-6 weeks. 
a Aerial. b One formula calls for 200 gm. of glucose per liter (Harter, 1913)* 
A comparison of the media with reference to their reaction (+ or —) 
has already been made. In this relation we have a sharp determining 
factor which eliminates many preparations. Other media, such as rice, 
may be taken as cases where a poor balance exists between the nitrogen 
supply and the carbon supply, thus setting up an unfavorable toxic 
condition. The com broth and the synthetic solution behave alike. 
The aerial growth seems to be strongest in substrata of an acid character. 
With rich substrata pycnidium production is aerial. The rapid pro¬ 
duction of pycnidia on filter paper is very significant. The wide range 
of suitable media is of great importance, and, since these substances 
must present carbohydrates and nitrogen compounds in great variety, 
