28 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 
over water in fruit jars. These cultures were kept for more than 
a year in an inside basement room in which the temperature was 
fairly constant (19 to 24° C). In no case did infection by wood- 
destroying fungi occur. The remaining amounts of the samples 
were kept in the original containers, which were capped with cotton 
and cloth. After 14 months no evidence of hymenomycete infection 
had appeared, although most of the samples were infected with one 
or two species of molds. 
This experiment is at least an indication that no infection from the 
rotten wood is carried through the grinding process. Undeniably, 
pulp made from infected wood does deteriorate faster in storage than 
that made from sound wood. (See Table 12.) This tendency 
would seem to be due to an increased susceptibility to infection rather 
than the bodily transfer of fragments of fungi from the wood. 
Woody or other organic materials infected with living fungi are, 
however, a common source of infection — a fact which is particularly 
noticeable with decay-producing fungi. Barnes (2) placed rotten 
pulp in sound pulp and incubated the bundles for several weeks. The 
results led him to believe that the infection would not be trans- 
mitted. This opinion is not supported by repeated observations of 
what actually takes place in commercial storage. Pulp may become 
infected not only by contact with infected pulp but also by contact 
with other decayed materials. Rotten wood floors in storage sheds 
and plank bases for pulp piles frequently infect pulp placed in contact 
with them, and the infection may pass upward through a considerable 
number of laps. Any infected wood placed within or in contact 
with a pile may spread decay. An interesting demonstration of such 
contagion occurred in one of the experimental piles, where certain 
planks picked up about the yard were used to separate the experi- 
mental material from surrounding mill stock. At the end of six 
months an infection with a wood-destroying fungus could be traced 
from the planks downward through as many as eight laps. 
The dirt carried on workmen's shoes and clothing is also a likely 
source of infection. The soil about pulp mills is loaded with fungi, 
and even small quantities transplanted to fresh, moist pulp are 
bound to start infections, each of which may eventually involve 
several hundred pounds of pulp. For this reason it would be highly 
advisable for each workman handling pulp to keep a pair of clean 
shoes for use on the pile only, and never to wear them anywhere else. 
Upon attention to just such details, to the layman apparently of 
little import, have been built up the highly successful practices of 
modern medical sanitation. 
There still remain two other possible sources of infection to be 
considered: Contaminated water used in the manufacturing proc- 
esses, and fungous spores carried by the air. 
Beadle and Stevens (4) hold that little infection comes from the 
water. They advance the idea that infection depends upon the food- 
yielding capacity of the wood, which varies with the season of cutting; 
that in the spring and summer the wood contains, in the pith rays, 
sugars and other organic food materials which are favorable to mold 
growth; that in the fall these foodstuffs are converted into insoluble 
reserve substances, such as starch, which are less available as food 
for fungi; and that the only part water plays in the contamination 
