HUMIDITY IN RELATION TO MOISTURE IMBIBI- 
TION BY WOOD AND TO SPORE GER- 
MINATION ON WOOD 
SANFORD M. ZELLER 
Assistant Plant Pathologist, Oregon Agricultural College and Experiment Station; 
Formerly Visiting Fellow in the Henry Shaw School of Botany of 
Washington University 
INTRODUCTION 
In a previous publication the writer (16) pointed out that 
between a certain minimum and maximum of moisture in wood 
Lenzites saepiaria and other similar wood-destroying fungi will 
grow and cause the destruction of the wood. "Thus, the power 
of wood to absorb moisture, whether as vapor from the air or as 
water from objects in contact with the wood, is a factor of prime 
importance in its susceptibility to decay. It is no less true that 
any property of the wood which may influence its moisture- 
absorbing capacity is a factor in its durability. In this con- 
nection it has been suggested (Zeller, '16) that, although resin 
has no actual toxie effect on the growth of wood-destroying 
fungi, it does inhibit growth when in large percentages and its 
only inhibitive power probably lies in the fact that it excludes 
water from the fibre containing it (Zeller, '17). 
With these previous results as a foundation further investiga- 
tions have been conducted to ascertain (1) the amount of mois- 
ture which wood will absorb from the atmosphere at different 
relative humidities when the temperature remains constant; (2) 
whether the water-proofing effect of resin on wood can be meas- 
ured; and (3) the relation of the moisture content of wood (or 
relative humidity of the atmosphere) to the propagation of wood- 
destroying fungi on wood. The purpose of the present paper 
is to report the results of these experiments. 
EXPERIMENTATION 
Materials used.—For the experiments reported below samples 
were selected from specimens of shortleaf pine (Pinus echinata) 
secured at the Fordyce Lumber Company, Fordyce, Arkansas, and 
from specimens of longleaf pine (Pinus palustris) secured at the 
ANN. Mo. Bor. Ganp., Vor. 7, 1920 (51) 
