752 
Journal of Agricultural Research 
Vol. V, No. 16 
approximately five times the strength. The experiments with mag¬ 
nesium sulphate are contradictory in part, but when the experience on 
page 742 is considered it may be concluded that for this organism the 
magnesium-sulphate ratio may be increased with profit. The phosphate 
proportion represented by Mjioo seems to be the favorable one. Sodium 
carbonate is found to be a constituent entirely unnecessary and for the 
most part detrimental to fruit-body formation. 1 
By this experiment, which could profitably be carried still farther 
within the limits indicated, a synthetic culture medium was obtained 
which gave for this organism a far greater pycnidia production than any 
other medium tried. 
The merits of this medium may now be considered. It is a solution 
which contains the minerals necessary for growth of a vigorous char¬ 
acter, but these chemicals are not present in superfluous amounts. It 
contains the carbohydrate which gave a remarkably strong, vigorous 
growth with this fungus, but the amount of the sugar is limited. The 
nitrogen source is a chemical of known composition and with maltose 
gave the strongest pycnidium production in the previous experiments. 
From the behavior of this organism we may conclude that we are ap¬ 
proaching an ideal culture medium for the growth and reproduction of this 
organism. But we may go even farther, since the physiological relations 
of fungi to the substratum are so much alike. We can safely say that 
this combination will be found widely useful in producing similar repro¬ 
duction in related forms. By the application of the same type of manip¬ 
ulation, some such combination can be found for other forms which will 
give better results than are now obtained on the ordinary media. 
We may now consider some of the ordinary laboratory media in their 
effects upon this organism. The fungus has been cultivated upon a 
great many of the ordinary materials used in the laboratory for .stock 
cultures and for diagnostic work. In this culture work the relation to 
light and to oxygen has been carefully observed. The relation to reaction 
has been but tardily recognized. The experience reported for pea broth 
shows that almost all relations to media can be reversed by changes in 
reaction (acidity or alkalinity). The initial relation is not, however, of 
as much importance as the reaction to phenophthalein after sufficient 
growth has taken place to lead to pycnidium formation. Table XXV 
summarizes the behavior of the organism on the complex media, with 
the relations on the synthetic solutions included for comparison. 
x For convenience the amounts used in preparing this solution maybe given. Stock solutions of M/5 
chemicals are prepared as follows: 
Magnesium sulphate+7 Aq. 2.466 gm.+so c. c. water. 
Potassium acid phosphate 1.36 gm.+so c. c. water. 
Asparagin 1.33 gm.+so c. c. water. 
Maltose 3.60 gm.+so c. c. water. 
For 100 c. c. synthetic solution take 1 c. c. of M/s magnesium sulphate and 5 c. c. of each of the other 
solutions, and add to 84 c. c. water. Steam on three successive days. 
