462 
JOHN A. ELLIOTT 
of the colonies on this medium was very similar to that on washed 
plain agar, although the appearance of starvation was not so em- 
phasized. 
Standard synthetic agar with double amount of glucose, jo°, 10 days: 
The aerial parts of the colonies, mycelium, conidiophores and spores, 
were more abundant than on the standard medium. The size of the 
spores of some species was much reduced (Graphs 4, 8, 9; Curve H). 
Standard synthetic agar with double amount of as par agin, jo°, 10 days: 
All colonies appeared less luxuriant than on the standard synthetic 
agar or bean agar. 
Standard synthetic agar minus asparagin, jo°, 10 days: Partial . 
starvation appeared in all species, and the submerged mycelium was 
darkened in most cases. The latter was most noticeable in A. solani 
from potato which usually had colorless mycelium. This same fungus 
produced a few spores on this medium, which was also unusual. 
Aerial mycelium was generally very meager in all species. 
Plain washed agar, 20°: But for the mycelium of Macrosporium 
sarcinaeforme, the only characters by which the different species could 
be identified were those of the spores and conidiophores which were 
natural (Plate XIX., i, 3, 5, 7, 8, 11, 16, 17; XX: 7, 9). Aerial 
mycelium was lacking and the submerged mycelium colorless and 
without distinctive features. Spores and conidiophores were charac- 
teristic. This was the only artificial medium upon which A. solani 
from potato produced spores in any abundance. A . solani, from Da- 
tura, did not produce spores until after eighty days. The torulose 
mycelium characteristic of this strain on most media was scarcely 
noticeable on the washed agar. Macrosporium sarcinaeforme pro- 
duced dark torulose submerged mycelium characteristic of the species. 
Variations under Different Conditions of Humidity 
The effect of humidity upon the colony characters was studied by 
keeping the cultures at 20° C. in saturated atmosphere; room humidity 
(variation 45-70 percent) ; and in an atmosphere kept dry by the use 
of calcium chloride. In order to prevent desiccation of the medium, 
all the plates were coated with a thin layer of paraffin. After the 
agar had hardened, hot sterile paraffin was poured over the agar and 
the excess poured off. This left a thin film of paraffin effectively 
protecting the medium from desiccation or contamination. The 
paraffin was punctured in several places by needle pricks and spores 
