22 BULLETIN 606, U. S. DEPARTMENT OF AGRICULTURE. 
tration could be obtained at any of the pressures used. Creosote was 
found chiefly in the vessels and very little in the wood prosenchyma 
or medullary rays. 
Elm, rock {Vlmus racemosa) — heartwood. — Bock elm is a ring- 
porous wood with interlaced fibers. Tyloses were generally few and 
scattered in the specimens treated. All of the specimens tested in 
both the penetrance apparatus and in the cylinder showed erratic 
penetrations. In most cases penetration took place in streaks, some 
of the wood being well penetrated and other parts entirely untouched. 
Specimens treated in the cylinder at the lower pressures showed a 
better absorption and penetration than specimens treated at the 
higher pressures. This may have been due to an irregular distribu- 
tion of tyloses in the specimens. The difficulty with which this wood 
takes treatment seems to indicate that the interlaced condition of 
the wood fibers may vary throughout the stick, thereby causing 
irregular penetrations. Most of the preservative was found to be in 
the vessels. There was very slight penetration in the wood prosen- 
chyma and medullary rays. 
Elm, slippery (Ulmus pubescens) — heartwood. — There are practi- 
cally no tyloses present in either sapwood or heartwood of slippery 
elm. On account of the open condition of the large and numerous 
pores, it was not possible to make anj^ tests in the penetrance ap- 
paratus. The creosote penetrated the wood largely through the ves- 
sels, but also to some extent in the wood prosenchyma. Good pene- 
trations w T ere easily secured on account of the large open pores. 
Elm, ivhite (Ulmus americana) — heartwood. — Tyloses were few 
1 and scattered in the specimens of white elm tested, and the penetra- 
; tion was chiefly in the vessels. The medullary rays and wood pro- 
| senchyma had only a slight penetration. Specimens treated in the 
cylinder showed good penetrations with most of the pressures em- 
: ployed. Fairly good penetrations were also secured in the pene- 
trance apparatus. 
Gum, red (Liqiddambar styracifiua) — heartwood and sapwood. — 
! Bed gum is rather heavy, moderately hard, and cross-grained. The 
fibers generally have thick walls and are arranged in definite radial 
rows. The species is diffuse-porous with pores numerous and uni- 
formly distributed. Tyloses are usually present and scattered in 
both heartwood and sapwood. Infiltrating substances are present to 
a large extent in the cell walls. It was difficult to secure an appreci- 
able penetration of the heartwood in any of the treatments. Speci- 
mens treated in the cylinder showed practically no radial or tangen- 
tial penetration. The difficulty in treating this wood was very likely 
due in a large degree to the infiltrating substances in the ceil walls, 
as well as tyloses, which prevented the preservative from entering the 
vessels in which they were well developed. The cross-grained struc- 
ture and thick walls of the fibers may also have been factors iniiuenc- 
