20 BULLETIN 606, U. S. DEPARTMENT OF AGRICULTURE. 
penetrated the wood very readily both in the penetrance and cylinder 
treatments. The penetrance was especially uniform in this species 
and the oil apparently reached all parts of the wood structure. 
Beech, red-heart (Fagus atropunicea) . — Keel-heart beech contains 
numerous tyloses in the heartwood and few in the sapwood. This 
wood was found to be very difficult to penetrate. Specimens treated 
in the cylinder showed only a very limited end penetration. A very 
small amount of creosote was found in the vessels and little or none 
in the wood prosenchyma. The difficulty of penetration seems to 
have been caused by the abundant tyloses found in the pores of the 
wood and b} 7 the infiltrating substances in the fiber walls of the " red 
heart " portion, which apparently prevented penetration in these 
elements. 
Birch, sweet (Betulu lento) — 'heartwood. — The fibers in sweet 
birch are thick-walled, and gummy substances are frequently found 
in the wood. Tyloses are not found in either sapwood or heartwood. 
Specimens treated in the cylinder were well penetrated even at low 
pressures. Penetration was found to be well distributed throughout 
the wood structure. The wood prosenchyma was fairly well pene- 
trated, but creosote was present to a greater extent in the vessels. 
Birch, yellow (Betulo lutea) — heartwood. — Yellow birch contains 
no tyloses in either sapwood or heartwood. The pores were very 
easily penetrated in ail of the tests. In the penetrance tests the pre- 
servative penetrated to the ends of the sticks almost immediately 
after pressure was applied. In the cylinder treatments the vessels 
were easily penetrated when the wood was merely immersed in the 
preservative for an hour. When pressure was applied both the ves- 
sels and wood prosenchyma were thorough^ treated. 
Birch, red {Betulo nigra) — heartwood. — The pores in red birch are 
somewhat larger than those in sweet birch. The wood fibers are 
fairly thin-walled and there are no tyloses in sapwood or heartwood. 
As in yellow birch, the vessels were rather easily penetrated at low 
pressures. At pressures of 50 pounds or more both the vessels and 
wood prosenchyma were well penetrated. 
Chewy, wild red (Primus pennsylvonica) — heartwood. — Wild red 
cherry does not contain tyloses. The wood was treated very easily 
and was found to be fairly well penetrated when merely immersed 
in the preservative for an hour. Penetration was complete in prac- 
tically all of the treatments made. 
Chestnut (Castanea dentata) — heartwood. — The pores in chestnut 
are numerous and are more or less filled with tyloses in both sapwood 
and heartwood. This species was very difficult to penetrate both in 
the penetrance apparatus and in the cylinder. Specimens treated in 
the cylinder showed very little radial or tangential penetration. The 
tyloses appeared to close the vessels, so that only a very limited pene- 
