466 
Journal of Agricultural Research 
Vol. I, No. 6 
A good absorption was obtained in both the sapwood and heartwood. 
Nevertheless, the tyloses, which were everywhere well developed and un¬ 
damaged in the large vessels of both regions, remained colorless and 
untreated. In addition, two other blocks of hickory from material col¬ 
lected with special care were also given pressure treatments in the cylin¬ 
der. These specimens were from pignut hickory, Hicoria glabra , and 
mockernut hickory, Hicoria alba . Both specimens contained sapwood 
and heartwood, with tyloses strongly developed in the large vessels. 
Again, the wood was thoroughly treated with creosote in both the sap- 
wood and the heartwood, and once more the tyloses could be observed 
on a split surface to be quite uncolored and visible even to the naked 
eye through their marked contrast with the blackish brown of the treated 
wood. (PI. LII, fig. i.) 
Thus, results from four specimens of hickory from different sources 
clearly showed that in spite of the presence of tyloses a high absorption 
of creosote may be obtained in the wood substance outside of the vessels 
and the tyloses filling them. 
The other species used in these experiments was the so-called red-heart 
beech, a form of Fagus atropunicea. This had white tylose-free sapwood, 
but a reddish heartwood with many tyloses. It was treated in the cylin¬ 
der at the same time as some of the hickories. The sapwood was thor¬ 
oughly penetrated, but the heartwood remained untreated except for a 
surface coating and a very slight infiltration near the ends. 
Lastly, a second piece of white oak was treated, as a check on the 
piece treated previously. After the creosote treatment, which was 
given at the same time as that of the hickories and beech, the sapwood 
was found to be penetrated, and, as before, the heartwood was unpene¬ 
trated. Careful examination showed, however, that the discoloration 
of the creosote extended down the large vessels of the sapwood and into 
the tyloses which they contained. This apparent contradiction of 
previous observations was explained when the material was examined 
under the microscope. The tyloses were found to be full of fungous 
mycelium and riddled with holes produced by the hyphse in passing 
through the tylose walls. Under these circumstances, even when abun¬ 
dant tyloses are present, it is clear that some penetration may be secured 
in the vessels. 
The marked difference to be observed in the penetrance of creosote in 
treatments of red oak and white oak is, however, chiefly the result of the 
presence or absence of tyloses. The unobstructed vessels of red oak 
give such open channels and offer so much additional surface for absorp¬ 
tion through their walls that the penetrability of the other elements 
lying between the vessels is of relatively little importance. In white 
oak, on the other hand, it is only the elements of structure other than 
the large vessels that are available for penetration. The type of pene¬ 
trance obtained in red oak is shown in Plate LIX, figure 2, A. The dark 
streaks mark the course of the creosote, which passed almost entirely 
