74 
BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 
experiments reported. As in the case of molds, some of the hymeno- 
mycetes have been observed to cause much more damage under 
normal conditions of storage than they did in pure culture tests. 
Among the factors contributing to this reduced activity of the 
fungi in certain of the artificial cultures, both temperature and mois- 
ture doubtless play an important part. No one temperature would 
be the one most favorable for the maximum growth of all the 54 
species tested. The temperature of 21° C, at which the cultures 
were stored, would be too low for the most vigorous growth of many 
of them. Laboratory temperature (approximately 22 to 28° C.) 
appeared to be better. (See PL XIX, figs. 2 and 3.) The moisture 
requirements may also vary greatly for the different fungi. (See 
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Fig. 3. — Graphs showing loss in weight of ground-wood pulp due to pure cultures of two wood-destroying 
fungi under two different moisture conditions 
fig. 3.) In some of the jars the pulp evidently became either too dry 
or too wet for the maximum growth of the fungi. (Refer to Table 
14 for pronounced variations in moisture content.) 
CHEMICAL PROPERTIES 
It has been demonstrated that the growth of the organisms of 
decay in wood pulp is accompanied in most cases by a loss in weight 
of the pulp. From data available in the technical literature (!#) 
it is evident that under the action of these organisms the complex 
wood substance is broken down into simpler compounds, some of 
which are water-soluble and some of which pass off as gases. With 
this in mind, a study was made to determine the changes in the chemi- 
