554 
Journal o f Agricultural Research 
Vol. XXIX, No II 
inches long. Special length test tubes 
were used with the 11-inch sticks. 
A plug of cotton 2 inches long was 
placed in the bottom of each tube, the 
stick was next inserted and 200 c. c. of 
distilled water poured in. The tubes 
were then autoclaved for 45 minutes 
at 15 pounds steam pressure. The 
sticks were next inoculated by placing 
a small fragment of ttye mycelial growth 
taken from a pure culture of known 
fungus upon the stick at a point ap¬ 
proximately 5 inches up from the 
base. 
In some cases the inoculum used was 
from pure cultures secured from spores 
or from sporophore tissue of the fungus. 
A piece of waxed paper was next placed 
over the cotton plug and fastened 
closely to the tube by means of a strip 
of heavy gummed paper. Most of the 
tubes were kept 8 to 12 months or 
longer before they were opened and the 
wood examined for results. In a few 
cases, 6 months or less produced the 
typical stage of decay in the portion of 
the stick where the moisture conditions 
were most favorable to the action of 
the fungus. At the end of the test, 
blocks were cut from the test sticks and 
cultures made from these in the usual 
manner (40). These were carefully 
compared with the pure cultures 
previously obtained and with stock 
cultures of known fungi secured from 
spores or from sporophore tissues. 
The results of the tests are given in 
Table V. Some of the fungi were in¬ 
oculated on various hosts in order to 
secure their reactions on each. Of the 
29 fungi used in the tests, 2 produced 
perfect sporophores and 4 produced 
poroid growths on the infected wood. 
Xylaria polymorpha produced sterile, 
black, club-shaped growths. 
In several cases the preference for 
the sap wood over the heartwood was 
quite pronounced and the organism 
developed rapidly and extensively on 
the sapwood blocks but barely covered 
the surfaces of the heartwood blocks 
(PI. 9, C and D). The effect upon the 
wood was found to be in somewhat the 
same relationship. For instance, Poly¬ 
porus adustus (?), Fomes igniarius, 
Fomes applanatus, Polyporus anceps, 
and Polystictus versicolor were inocu¬ 
lated on both sapwood and heartwood 
blocks and all five appeared to develop 
more rapidly upon the sapwood. 
The results secured by inoculating 
Tilia americana with Zylaria poly- 
morpha were very striking. The typi¬ 
cal white spongy-rot accompanied by a 
narrow black zone line formed across 
one end of the block (PI. 11, A) was dis¬ 
closed up6n splitting open the block. 
The surface of the block and the cotton 
in the bottom of the tube were covered 
in spots with grayish-black mycelial 
wefts and with the thin black crustlike 
layers so typical of the roots of Acer 
saccharum infected with this fungus. 
Sterile fruiting bodies also appeared at 
the base of the blocks. 
The typical brown cubical rots of 
Lenzites sepiaria and of Polyporus 
schweinitzii, charcoal-like in consist¬ 
ency, were produced artificially in 
blocks of Picea sitchensis (PI. 11, Band 
C) and of Lentinus lepideus , Fomes 
laricis, Fomes roseus } and Fomes pini- 
cola (PI. 8, A to H). The rot pro¬ 
duced by Lenzites sepiaria showed a 
greater tendency to form numerous 
shrinkage cracks which divided the 
rotted wood into small cubes. 
The rot produced artificially in Picea 
sitchensis and Tsuga heterophylla by 
Trametes pini is quite typical (PI. 11, D). 
White pockets are numerous and typical 
narrow brownish zone lines are formed 
across and .close to the ends of the pieces. 
The wood surrounding the pockets is 
stained reddish to reddish brown. 
A valuable cultural character (which 
unfortunately does not always develop) 
is the production in pure cultures of 
near-typical to typical sporophores 
from which mature spores are often 
cast (PI. 10). The sporophores, though 
diminutive, are frequently character¬ 
istic enough for identification and the 
spore casts furnish a means of checking 
the purity of the culture, as well as 
the character of the spores. 
A cultural method using sound 
sterilized wood as a medium and in 
vitro applicable to the study of un¬ 
identified wood rots will be found 
helpful in verifying the identity of 
causal fungi in regions where the rots 
are numerous and where the sporo¬ 
phores rarely develop. In the younger 
stands of timber old enough to contain 
rot but too young to bear sporophores 
of the"rot fungi, this type of cultural 
test will serve as a valuable check of the 
data obtained from a study of the gross, 
microscopical, and cultural characters. 
EXPLANATORY LEGEND FOR PLATE 8 
Brown rots produced by inoculation, showing typical rot with characteristic shrinkage in the rotted areas 
A and B. —Fomes laricis, taken from Pseudotsuqa taxifolia, on Picea sitchensis. C .—Lenzites sepiaria on 
Picea sitchensis. D. —Fomes roseus , taken from Picea canadensis, on Pinus strobus. E. —Lentinus lepideus, 
taken from Pinus taeda, on Picea sitchensis. F. —Fomes laricis on Pinus strobus. G — Trametes carnea 
on Pinus strobus. H.— Fomes pinicola, from Tsuga heterophylla, on Picea sitchensis .—Eight-elevenths 
natural size. 
