72 
BULLETIN" 1298, U. S. DEPARTMENT OF AGRICULTURE 
per cent was lost. The average loss was 14.4 per cent. In 12 
months from 5.5 to 40.2 per cent was lost; average, 18 per cent. 
The four sets of tests in which the fungi died are not counted in the 
results. 
The loss in the check cultures shown in all three tables is to be 
attributed to the changes brought about by sterilization and drying 
and to some slight loss due to handling; hence an experimental error 
of from ±0.4 to ±0.6 per cent should be allowed in all cases. ' 
It will be observed that in some instances the loss in weight in 12 
months was less than in one of the shorter periods. The following 
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Time —months 
Fig. 2.— Graphs showing loss in weight of ground-wood pulp after infection in pure culture by various 
wood-destroying fungi 
facts are offered in explanation of this apparent anomaly: Some, at 
least, of the tests indicate a decrease in the vitality of the organisms. 
Moreover, the weight of the fungous mycelium has not been taken 
into account; this will vary considerably, according to the nature 
of the fungus in question, and may amount to as much as several 
grams. Buromsky (8) reports a growth of 2.4 grams for Aspergillus 
niger when grown in favorable culture solutions, whereas some of the 
species used in the tests, especially among the hymenomycetes, 
produce a much more luxuriant growth of mycelium than does 
Aspergillus niger. 
