1920] 
ZELLER—IMBIBITION BY WOOD AND SPORE GERMINATION 67 
ing effect upon the wood containing it, and that this water- 
proofing effect is considerable as the fibre-saturation point is 
approached. In the shortleaf heart-wood at a relative humidity 
of 95 per cent the moisture absorption was decreased 15.6 per 
cent by 17.6 per cent resin, and at 100 per cent humidity the 
minimum moisture decrease was 20.8 per cent, and the average 
decrease was 31.5 per cent brought about by 17.6 per cent resin. 
In the longleaf pine heart-wood at a relative humidity of 95 per 
cent a resin content of 16.4-19 per cent had a water-proofing 
effect of 17.4 per cent, while at 100 per cent humidity the water- 
proofing effect of 18.4 per cent resin averaged 29.3 per cent, with 
a minimum of 21.5 per cent reduction in the moisture content. 
Undoubtedly, this water-proofing effect of resin has its in- 
fluence upon the durability of structural timber placed under 
very humid conditions, providing the resin content is sufficient 
to lower the moisture content of the wood below that which is 
conducive to the growth of wood-decaying fungi. Although the 
resin does have some influence in this direction, it is probably not 
sufficient to be relied upon as a test of durability. More reliance 
could be put upon resin as an index of durability in timbers con- 
taining, for example, 12 to 15 per cent resin, providing there was 
any reason to believe that it was equally distributed throughout 
the timber. With such an equal distribution of the resin the 
water-proofing would undoubtedly be more effective at lower 
relative humidities. Not only this, but mechanical resistance 
of resin equally distributed would undoubtedly be a great factor 
in the inhibition of fungous growth in the wood. This, however, 
is not the case. The resin is deposited in streaks in wood so 
that there are portions relatively free from resin. These 
resin-free portions, having a hygroscopicity sufficient to take 
up considerable moisture under the right moisture conditions, 
become sources of weakness because of the inroads of wood- 
destroying fungi. Examples of such decay are often reported 
as very destructive to the ceilings and structural timbers under 
the highly humid conditions produced in the paper- and pulp- 
mills of the eastern states and Canada and the knitting-sheds of 
the cotton industries of New England. Further experimenta- 
tion along this line is advisable. Some practical process of 
treating resinous lumber, possibly by modifying the kiln-drying 
