Feb., 1921] 
THOM AND CHURCH — ASPERGILLUS 
describing A. pseudoflavus, Saito^^ observed that exposure to ammonia 
would destroy the green color entirely, leaving yellow or yellowish brown. 
Subsequent exposure to vapor of acetic acid restored the green color to this 
colony. The test used by Saito was applied to A. flavus (no. 108, the 
Wehmer strain), A. oryzae (the sake organism), and A. parasiticus, which 
represent the widest range of differences in our collection. Each of these 
strains gave the reactions described by Saito for A. pseudoflavus. The 
test was repeated with hydrochloric acid substituted for acetic acid. The 
correlation of the green color with the acid was clearly brought out. These 
strains grown in Czapek's solution agar are, respectively, A. oryzae about 
lime green, A. flavus near Kronherg s green, and A. parasiticus close to ivy 
green, all in column 25", Plate XXXI of Ridgway's tables. When exposed 
to the fumes of hydrochloric acid the green color was intensified, reaching 
colors given in column 29'' of the same plate with the deepest areas reaching 
the same intensity, cress green. When the same cultures were exposed to 
ammonia, all of the green disappeared, and the colors remaining corresponded « 
with combinations in column 21" , Plate XXX, varying from deep colonial 
huff to olive in the deepest areas. 
In the experiments previously described the green colors are found 
present in marked degree only upon media containing sucrose or some other 
fermentable carbohydrate. In cultures upon beef, fish, egg, and soy beans, 
which lack carbohydrates or are very poor in fermentable carbohydrates, 
the greens were absent or nearly so throughout the series. In the mixtures of 
fermentable carbohydrates and proteins there are evidently simultaneous 
acid and alkaline fermentations which tend to neutralize each other as 
described by Ayers and Rupp.^^ 
The early development of conidia always shows some development of 
green in such cultures. When litmus is used in the culture medium, these 
early stages are always accompanied by the acid or red reaction. Many 
such cultures eventually lose all their green color, but this loss is always 
preceded by change in reaction. If a series of these strains grown upon a 
single medium show different shades of green, these shades of green are 
thus indications of the relative acidities reached by the culture. Some 
correlation between the typical color shown by a colony and the progressive 
changes in tl^ie reactions of the substratum, and possibly even of cytoplasm, 
is indicated. 
The substratum influences the development of such saprophytic fungi 
in numerous directions. The gross appearance of a pure mold culture may 
be entirely altered through the influence of the medium on which the 
fungus is growing. The dimensions of certain structures in an Aspergillus 
Saito, K. Microbiologische Studien iiber die Zubereitung des Batatenbranntweines 
auf der Insel Hachijo (Japan). Centralbl. Bakt. II, 18: 30-37. figs. 1-22. 1907. 
^3 Ayers, S. H., and Rupp, P. Simultaneous acid and alkaline fermentations rom 
dextrose and the salts of organic acids respectively. Jour. Infec. Dis. 23: 188-216. 1918. 
