68 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 
last sterilization they were transferred immediately from the auto- 
clave to the inoculating case, in which they were allowed to cool. 
Sets of three jars each were inoculated with a pure culture of a 
fungus that had been isolated from pulp, pulp-wood, boards from 
pulp sheds, or river water. The following two methods of inocula- 
tion were used: 
1. In the case of molds, a sporulating culture on a malt agar slant 
was used as the source of the inoculum. Five cubic centimeters of 
sterilized distilled water were poured into the culture tube, which was 
thoroughly shaken until a heavy spore suspension was obtained. 
Then three test tubes containing sterile water were opened and a 
third of the spore suspension was poured into each. The three spore 
suspensions resulting were then used to inoculate the pulp samples. 
One side of the jar cover was carefully lifted and the spore suspension 
poured over the tops of the pieces of pulp in the jar. Care was exerted 
to have the inoculation of the pieces of pulp as nearly uniform as 
possible, so as to establish a check. 
2. The cultures inoculated with wood destroyers were treated as 
follows : Petri-dish cultures of the fungus in question were made on 
malt agar a week in advance, after which time they were cut into 
pieces about 8 millimeters square, and one square was placed on the 
top of each of the three pieces of pulp in the jar. The jars, as in- 
oculated, were removed from the culture case. New rubber bands 
were substituted for the old ones, and white papers, to keep the dust 
from the caps, were placed over the tops and held in place by heavy 
rubber bands. 
All the jars were then stored in an inside basement room in which 
the temperature was fairly constant (average 21° C). The three 
jars of each set were opened at the end of 6, 9, and 12 months, re- 
spectively. At the end of the test the moisture content of the samples 
was determined, and the loss, based on oven-dry (100 to 105° C.) 
weight, was obtained for each culture. As each jar was opened the 
small extra piece of pulp was transferred to a sterile Petri dish and 
small pieces of it were then planted upon malt agar plates. The 
object of this procedure was to determine whether or not the fungus 
had remained viable throughout the experiment and whether the 
culture had remained pure. Results in these respects were positive 
except in the cases specially noted in the tables. 
DATA AND DISCUSSION 
Table 14 gives the results obtained with 29 cultures of molds, 
representing at least 26 distinct species. The loss in weight was small 
in all the mold-inoculated pulps. Trichoderma sp. (6520-2) caused 
the greatest loss in 12 months, 3.2 per cent. Four samples became 
some shade of pink, and nine became gray. Only three samples, 
which were gray, were dark enough to have spoiled the quality of 
paper made from them. The remaining 16 samples were recorded 
as " normal," which means that (1) the pulp itself* retained its usual 
color; (2) the fungus did not make the pulp brittle, or, in so far as 
could be determined macroscopically, otherwise change its physical 
properties; and (3) the colored spores of the fungus, produced on the 
surface of the pulp, were in sufficiently small numbers and of such 
kind that they would ordinarily be washed off in the beater without 
causing any damage to the manufactured paper. 
