[Vor. 4 
146 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
TABLE IV (Continued) 
DECAY OF RESIN-IMPREGNATED YELLOW POPLAR BLOCKS INDUCED BY 
POLYSTICTUS HIRSUTUS 
Weight Weight Per cent 
eee before decay after decay loss in телде 
ы: (gm.) (gm.) eight 
Z9 2.769 13.401 0.30 12.41 
Z 10 „781 11.257 4.4: 13.20 
#11 9.329 15.108 44 10.40 
2512 4.727 14.620 0. 10.50 
4, 14 .832 9.903 16.30 13.48 
Z 14 .035 9.347 22. 12.34 
X2 5 ),119 10.936 9.76 t0 
Y 0.324 8.931 13.50 10 
YZ 10 .698 11.940 12.5 +0 
YZ 11 3.162 11.686 11.20 70 
YZ. 12 .286 9.660 4.4 10 
YZ 13 073 10.761 ).88 10 
YZ 14 2.902 11.369 90 10 
¥Z- 15 0.772 9.436 2.40 10 
t Not treated with benzene. | 
DISCUSSION 
Before entering upon a discussion of the specific factors of 
wood which influence its resistance to decay, it might be well 
to call attention to some factors of the environment which 
influence fungous activity in general. In a problem of this 
kind, where the results depend on natural conditions and also 
to a certain extent on chance or probability of infection, the 
results may be misleading unless such factors are considered. 
In any work where a host is inoculated with an organism 
one anticipates a certain percentage of failures, even though 
the host is susceptible and the parasite virulent. The chance 
of failure of infection seems to be even greater when we deal 
with the inoculation of woody rather than of more fleshy her- 
baceous plants; especially is this true when dealing with fungi 
attacking structural timber. Іп the cultures of Leneites 
saepiaria on blocks of yellow pine, described above, the per- 
centage of failure proved to be very high. The charts to be 
discussed below certainly show this to be a fact. Itis true for 
sap-wood as well as for heart-wood, even though sap-wood 
decays much more readily than heart-wood. In the same col- 
umn of blocks of the same sample one culture block may be 
considerably decayed and others not at all; for instance, in 
table 1 culture block Е 1603 was reduced in weight by decay 
