Mar. 25, 1914 
467 
Tyloses in American Woods 
through the open vessels. The practical effect of this is evident in the 
results obtained in penetrance treatments. It is possible to force creo¬ 
sote for long distances through red oak just as it would be possible to 
force it through similar distances in small open pipe lines. In com¬ 
parison with this, the distance the oil will pass through white oak is very 
short, since it has to penetrate through many cell walls, and the resistance 
of the material must be overcome by high pressures. 
Thus, although tyloses have a distinct effect, they are not the only 
factor in the penetrance of wood. The characteristics of the other 
elements in the annual ring must be considered. However, in the cases 
examined, wherever the large vessels contained abundantly developed 
tyloses or filling cells, the vessels and the tyloses, but not necessarily 
the rest of the woody tissues, were impenetrable to creosote. 
OBSERVATIONS ON CONIFERS 
The presence of resin canals and their condition—that is, whether they 
are open or partly or entirely closed by cells—considered in conjunction 
with the general permeability of the tracheids, is a factor of practical 
significance in the selection of wood for creosoting. (Pis. LVI and LVII.) 
The number of the resin canals is very small in comparison with the 
number of tracheids. However, if the canals are unobstructed, pene¬ 
trance is easily obtained for considerable distances through their cavities. 
In a wood whose tracheids are penetrated with difficulty, the creosote 
does not spread to any great extent from the canals into the tracheids, 
even when the former are full. Nevertheless, the presence of creosote 
or other toxic liquid in the resin-canal regions, which are among the first 
affected by fungous infection, is of considerable assistance in prolonging 
the life of the wood. Many of the resin canals, especially the vertical 
canals in both the sap wood and the heartwood of the pines, are not com¬ 
pletely closed (PI. TVII, fig. 1, and PI. TVIII, figs. 1 and 4) and can 
for this reason be penetrated. The effect of the presence or absence 
of tylose-like cells in the resin canals, while a minor factor, is significant 
in connection with the treatment of poles, ties, and paving blocks. 
EFFECT OF TYEOSES ON THE WATER-EOGGING OF WOOD 
In order to test the effect of tyloses on the water-logging of wood, some 
roughly comparable air-dry blocks of several species were placed in a tank 
of water and the length of time required to water-log each block suffi¬ 
ciently to sink it was noted. The blocks were grouped with reference to 
their specific gravity (dry) 1 and their actual weight. The woods in which 
tyloses were few or wholly lacking invariably sank before those contain¬ 
ing abundant tyloses. Chestnut oak sank before white oak and bur oak, 
persimmon before osage orange, flowering dogwood before hickory, yel¬ 
low poplar and aspen before catalpa, and blue beech and honey locust 
1 Sargent, C. S. Report on the Forests of North America ... 612 p., maps. Washington, 1884. 
(U. S. froth Census Reports, v. 9].) 
