Jan, 17, 1916 
Plenodomus fuscomaculans 
765 
to its environment and by manipulation of the environmental factors to 
discover the various phases of life history. Although many related 
forms have been grown in pure culture, very little physiological work of 
this type has been done with the Sphaeropsidales. 
The organism was found to have a wider range of conditions suitable 
for growth than for reproduction. The base level of conditions neces¬ 
sary for growth is found in conductivity water at low temperatures. 
Reproduction requires more favorable conditions. Pycnidium pro¬ 
duction took place only in cultures exposed to light. The ordinary 
room temperatures were sufficient. Abundant aeration is essential. 
Transpiration is a factor of secondary importance. A slight acid reaction, 
especially at the close of the growing period, is a necessary condition. 
The value of a medium depends largely upon the acid or alkaline reac¬ 
tions present, not alone at the beginning but at the close of the growing 
period. Autointoxication was observed and was traced to excess of 
either acid or ammonia, which was the product of too great a proportion 
of either carbohydrate or protein, respectively. 
As has been said, the quantity of foodstuff necessary for growth is 
extremely minute. Pycnidium production requires more food, but the 
meager amount present in distilled water is sufficient to allow the pro¬ 
duction of a few pycnidia. On the other hand, the fungus is able to 
tolerate very rich food supplies, but pycnidium production in solutions is 
restricted to M/100 or perhaps M/50 sugar concentration. Exact limits 
, are hard to determine, because of the formation of mats or films in solu¬ 
tions, which effectively wall off much of the food supply. Fructification 
in the case of rich media takes place in the aerial hyphae, and no doubt 
this relation corresponds with the conditions in solutions. 
Magnesium sulphate and potassium dihydrogen phosphate in very 
dilute solutions furnish the necessary mineral elements for growth and 
reproduction. The carbon supply may be taken from a wide range of 
compounds of alcoholic structure. The carbohydrates furnish food 
materials in most available form, and, of these, xylose and maltose pro¬ 
duce the best growth. The carbohydrates do not seem to be specific in 
producing fruiting bodies, and almost any are suitable if taken at the 
right dilution. The nitrogen assimilation is greatly influenced by the 
type of carbon nutrition. 
The minerals mentioned and maltose and asparagin at the ratio of 5 to 1 
seem to offer the most favorable combination, although others are 
suitable. From the experiments a medium was selected which though 
of entirely known composition gave better growth than any other tiled. 
This synthetic solution had a scant amount of food supply, yet enough 
to permit a quick, vigorous growth. It retains the acid reaction till the 
, close of the growing period. A study of this medium gave a basis for a 
criticism of results obtained with the common laboratory combinations. 
