195] SCALES—FILAMENTOUS FUNGI I5I 
undertaken for the purpose of determining more species of the 
filamentous fungi that are capable of exercising this function. 
Dr. CHARLES THOM, mycologist of the Bureau of Chemistry, 
kindly supplied us with the 30 species of Penicillium and 10 species 
of Aspergillus that were used in this work. The cellulose destroy- 
ing power of these organisms was determined with two different 
sources of nitrogen. An ammonium sulphate cellulose agar and a 
peptone cellulose agar were used for this purpose. The ammonium 
sulphate medium was prepared by the method described in a 
previous publication,® and the peptone medium by substituting 1 
gram per liter of peptone for the ammonium sulphate. 
The stock ‘cultures were kept on Czapek’s agar. The spores 
from fresh growths on this medium were added to freshly poured 
duplicate cellulose agar plates of both media. The plate cultures 
were inoculated in four places. Test tube cultures on both media 
were also made in duplicate at the same time. The Petri dishes 
were placed in moist chambers and then put in the incubator along 
with the tube cultures, which were kept at 28-30° C. for two 
months. They were then examined for an enzymic zone either 
around the colony on the plates or underneath it in the tubes. 
The size of this enzymic area varied considerably in the different 
cultures, ranging from a very thin clear zone less than 1 mm. to 
one 24 mm. deep in some of the tubes. Although the depth of the 
clear zone was fairly constant in the duplicate tubes, this phase 
of the work will not be emphasized until more data are obtained. 
As the surface growth on cellulose agar is frequently scanty, 
with few definite microscopic differences, it seemed best to trans- 
plant from the plates and tubes onto Czapek’s agar, in order to 
check each organism that destroyed cellulose against a growth on 
Czapek’s agar made from the stock material of this species. A 
microscopic examination was made in each case. 
The results are given in the accompanying table. The appar- 
ent failure of a number of the organisms fermenting cellulose with 
ammonium sulphate as the source of nitrogen to do the same with 
peptone as the source of nitrogen may be accounted for in two 
ways. One is that the organisms produced such an abundant 
sterile growth in the medium that any slight clearing was obscured; 
