CONTROL OF DECAY IN PULP AND PULP WOOD 55 
MATERIALS AND METHODS EMPLOYED 
In the study here reported, fungi were isolated from 18 samples 
of ground wood, 5 samples of sulphite pulp, 1 sample of soda pulp, 
8 pulp logs, 7 boards taken from pulp sheds, 1 sample of white water, 
and 4 samples of river water. Although no attempt was made to 
obtain in pure culture all of the fungi that are in any way responsible 
for the deterioration of wood pulp, the writers nevertheless feel con- 
fident that they have isolated all of the more serious enemies common 
to pulp in the localities from which pulp samples were received. 
These samples, either in single laps or in larger amounts up to ap- 
proximately half a ton, were submitted from mills in New York, 
Wisconsin, Minnesota, and Canada. Other samples of water were 
plated out, but since they yielded neither cellulose-dissolving molds 
nor hymenomycetes, no further study of them was made, nor were 
the cultures which they produced retained. 
All culture work was performed in a culture case kept sterile by 
careful washing out with mercuric chloride solution (1:1000) before 
each using. 
For general purposes, plain malt agar, made up according to the 
following formula, was found to be a very favorable medium: 
Distilled water cubic centimeters, _ 1, 000 
Trommer's plain malt extract grams__ 25 
Agar-agar, powdered or Bacto (acidity not adjusted) do 15 
Approximately 20 cubic centimeters were put in each test tube. 
After sterilization the medium was poured from the tubes into sterile 
Petri dishes, 3 or 4 drops of 5 per cent lactic acid having been added 
to half the tubes just prior to pouring. Both plain and acidified 
plates were then used in plating out the pulp samples. In special 
cases, in which the fungus could not be made to grow upon the plain 
malt medium, potato, carrot, bean, prune, and oatmeal agars were 
tried. In no case, however, were cultures obtained on these special 
media when they would not grow on the plain malt agar. For 
making cultures from river water, McBeth and Scale's cellulose agar 
was used. 
Characteristic spots on the pulp were selected. ' In the compara- 
tively few cases in which surface spores were present, a platinum 
loop full of sterile water was brought into contact and the adherent 
spores were transferred to a sterile tube containing about 2 cubic 
centimeters of distilled water. After a thorough shaking of this first 
tube further dilutions were made. Then a few drops of the spore 
suspensions were poured upon plain malt and acidified plates, and 
each plate was shaken gentry until the entire surface was covered 
with a thin layer of the water. The plates were then incubated at 
25 to 30° C. for the necessary period, which varies considerably 
with the various species of fungi. If the colonies on the plates were 
fairly uniform and sufficiently scattered, some of them were trans- 
ferred to malt slants before any of them had sporulated. If mixed cul- 
tures were obtained, as was usually the case, the best plates were held 
until the desired fungus sporulated, when more plates would be made 
from it and the process repeated until pure cultures were obtained. 
On the majority of the pulp samples, however, the spots were 
apparently pigmented or bleached areas with no superficial spores, 
and the process above described was not applicable. In such in- 
