RESISTANCE OP CONIFERS TO CREOSOTE INJECTION. 29 



LODGEPOLE PINE (PINUS MURRAYANA). 



The growth rings of lodgepole pine were broad, with the summerwood about 

 one-fourth the width of the springwood. The transition from one to the other 

 was gradual. Resin cells were entirely absent. Resin canals were rather small ; 

 numerous, and mostly in the summerwood ; radial ducts were few. 



The average oven-dry weight per cubic foot of six heart specimens was 23.4 

 pounds, and of six sap specimens, 22.9 pounds. 



The heartwood of lodgepole pine greatly resisted treatment, and resisted lon- 

 gitudinal penetration nearly as much as radial. What penetration occurred 

 took place through the longitudinal and radial resin ducts. From these the 

 summerwood was more or less treated, and occasionally a medullary ray (not 

 fusiform) was found to be penetrated. In the tracheids, even when a pressure 

 of 90 pounds was applied for one hour (piece 166), the penetration longitudi- 

 nally was not deeper than the length of three cells, and tangentially not over 

 six cells, and then very light. The treatment seemed to take place chiefly 

 through the radial ducts, the oil passing to the longitudinal ducts wherever the 

 two intersected. 



In the cylinder most of the resin ducts appeared to be treated, and one split 

 section showed creosote in the center of the piece. Cells surrounding the 

 treated ducts in the summerwood appeared to be treated farther than equiva- 

 lent cells in the springwood. 



The sapwood was variable in its penetrability. Two of the pieces were pene- 

 trated radially in 30 to 45 seconds, the oil flowing copiously from the tangen- 

 tial surfaces almost as soon as pressure was applied, while the other piece 

 required 20 minutes to be penetrated radially. The nonresin structure was 

 very easily treated in both springwood and summerwood, but more quickly 

 in the latter. The medullary ray cells also were usually treated. 



In the cylinder the sapwood treated very easily, and even in the light treat- 

 ments both springwood and summerwood were saturated. So easily was the 

 sapwood treated that no difference in absorption was evident between pieces 

 soaked in hot oil (run 7) and others treated at a pressure of 150 pounds 

 (run 6). 



It is evident that in a thorough treatment of large timbers of this species 

 the sapwood will be completely treated while the heartwood will be penetrated 

 radially from 1 to 2 inches. The average longitudinal penetration was about 

 one and one-half times the radial ; the tangential penetration could not be 

 determined, but was probably negligible. 



JACK PINE ( PINUS DIVARICATA). 



The summerwood of jack pine was dense, and about one-third the width of 

 the springwood. Resin canals were small, numerous, chiefly in the summer- 

 wood, and contained tyloses. Radial ducts were not numerous. 



The average oven-dry weight per cubic foot of five heart specimens was 25.4 

 pounds. 



In the heartwood of jack pine longitudinal penetration took place first 

 through the resin ducts, from which the oil passed into the surrounding cells. 

 Summerwood was penetrated much more easily than springwood, and usually 

 all summerwood bands were treated. The springwood was not, however, very 

 difficult to penetrate, as this also contained many resin ducts. Treatment was 

 comparatively rapid in the radial resin ducts; from these the penetration was 

 diverted to the longitudinal ducts wherever the two sets crossed. 



In the cylinder sapwood was treated first in the summerwood. The spring- 

 wood also treated very quickly, and in the heavier treatments both springwood 



