740 
Journal of Agricultural Research 
Vol. V, No. 16 
The experiment shows that the ordinary high-grade filter paper, when 
autoclaved with water of high purity, yields sufficient nutriment for 
growth and reproduction of this organism. A dilution of i/ioo is still 
sufficient for pycnidium production, but at 1/1,000 we have reached the 
limit of food supply sufficient for pycnidium production. Growth, as 
usual, takes place at greater limits than reproduction. 
This experiment gives conclusive evidence that the toxic substances of 
distilled water do not affect this organism. We may now conclude that 
. we have been working nearer and nearer the limits of growth and repro¬ 
duction. The amount of material required is evidently extremely mi¬ 
nute. It is in the imponderable mass of stuff, somewhere between dis¬ 
tilled water and conductivity water, or in that bulk of stuff lying between 
1/1,000 and 1/10,000 dilution of a filter-paper broth. 
Having now some conception of the extremely low limits of concentra¬ 
tion at which growth may take place, we may now consider the growth 
and reproduction relations at higher concentrations. 
The experiments already reported give a mass of details as to growth, 
at various concentrations, but no conclusions from these isolated cases 
are justified, because the reaction is so masked by other relations. 
The following experiments allow a comparison of some nutrient solu¬ 
tions at various concentrations. The solutions chosen were those which 
did not become toxic with the continued growth of the organism. In one 
experiment 200 grains of corn were autoclaved in 1 liter of tap water. 
This solution was concentrated to approximately 100 c. c. by boiling in 
a beaker. It was, therefore, approximately 10 times the strength of 
ordinary corn broth. The strong solution was also diluted as shown in 
the table. Cultures were made as usual and were inoculated with a 
spore suspension. The results are shown in Table XVIII. 
Table) XVIII. —Effect of quantity of food: Test with corn solution 
[Time, i month] 
Concentration. 
Pycnidia. 
Growth. 
Remarks. 
10X. 
+++ 
+ 
+ + + + + 
+ + + + 
+ + 
+ 
White. 
White. 
Blackened. 
Blackened. 
cX.. 
iX. 
1/10X. 
In this experiment it is seen that the organism, after a month, pro¬ 
duced fruiting bodies only in the lower concentrations, but the growth 
was strong in the higher concentrations. The growth in the weaker con¬ 
centrations had increased but slightly after the first two weeks. We may 
conclude then that a food supply which allows a fair growth and then 
becomes exhausted is most favorable for pycnidium formation. 
The following experiment with synthetic media was performed. The 
combination described upon page 752 was made up at 25 times the usual 
