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S. Reginald Price. 
tained most of the hyphse which had entered. Hyphse had also 
penetrated a few of the outer layers of tracheids, usually by means 
of the bordered pits. A little delignification had occurred in the 
elements thus attacked, but the amount of cellulose produced was 
not great and was quite confined to these tracheids. 
IV. Infection of the Living Trees. 
(a). Mycelial Inoculations. Apparently no successful infections 
of living trees have yet been reported. 
To try to trace the method of infection and penetration inocu- 
culations were made on young Elm trees planted at the Botanic 
Garden, Cambridge. I should like here to record my thanks to 
Mr. Lynch, the Curator of the Garden, for his help in this 
connection. 
In the first place inoculations were made on May 6, 1912, with 
pieces of mycelium grown in pure culture on Elm wood. The 
mycelium was placed in scalpel wounds made both on healthy and 
dead branches, the wounds being subsequently covered closely with 
tin-foil and bound with wool (cf. 4, p. 136). On July 5, two twigs 
were removed and examined for hyphse, one twig having been dead 
at the time of inoculation, the other healthy. Hyphse were 
distinctly but sparingly present in the dead twig, but no sign of 
hyphse was found in the twig that had been living. The mycelium 
present in the dead twig had the characters of that of P. squawosus 
as appearing in the culture experiments, hut there is the danger 
with a dead twig that hyphse of another fungus may have already 
been present. 
Another twig living at the time of inoculation was examined on 
October 12, and again no mycelium was found. 
Mycelial inoculations were made on an old wound-surface and 
on one freshly made on the same living branch on October 18, 1912. 
The whole branch was removed on January 21, 1913, and the two 
inoculations examined. From the inoculation of the old wound- 
surface, hyphse had penetrated the vessels and other elements of 
the wood fairly freely and had effected a radial penetration more 
than half way to the centre of the branch (about 9 to 12 mm. diam.) 
in the interval October 19 to January 21. The lateral penetration 
below the old wound was slow, and the hyphse spread more quickly 
in a longitudinal direction, although during the interval October 19 
to January 21 the hyphse had spread only a distance of about 12 mm. 
above and below the limits of the inoculated surface. The hyphse 
penetrate the vessels more freely than the other elements. 
