RESISTANCE OP CONIFERS TO CREOSOTE INJECTION. 31 



and summerwood were saturated, resulting in very heavy absorptions. These 

 are not evident in the absorption data, because the sapwood specimens really 

 contained at least 50 per cent of heartwood. This .condition was unavoidable 

 because of the very thin sapwood that was available. 



Radial penetration was an important factor in this species. In the heart- 

 wood it averaged from one-eighth to one-fourth as great as the longitudinal 

 penetration; the tangential was only about one-eightieth of the longitudinal. 



WESTERN YELLOW PINE (PINUS P0NDEK0SA). 



The summerwood of western yellow pine was variable, dense, and was from 

 one-third to one-half the width of the springwood. The spring tracheids 

 were rather thick-walled. Resin passages were of medium size, numerous, and 

 located chiefly in the summerwood. Radial ducts were also numerous. 



The average oven-dry weight per cubic foot of sis heart specimens from Cali- 

 fornia was 25 pounds, and of six sap specimens 23 pounds; of six heart speci- 

 mens from Montana 25.4 pounds, and of five sap specimens 27.4 pounds. 



In the heartwood of the western yellow-pine specimens from California the 

 summerwood treated more easily than the springwood. Usually the entire 

 summerwood band was penetrated, and often many of the springwood tracheids 

 were heavily treated. The longitudinal and radial ducts were the channels 

 through which the penetration first took place, and from these it passed into 

 the summerwood. When springwood was treated, the oil seemed to come 

 from radial ducts and usually did not penetrate far from them. In the speci- 

 mens from Montana the summerwood treated first, as in the California speci- 

 mens, but the outer summer tracheids had the heaviest absorptions and were 

 treated for the greatest distances. The springwood was untreated except for 

 isolated tracheids which were penetrated from the ray ducts. 



In the sapwood of the California specimens penetration took place very rapidly 

 in the resin ducts, but throughout the tracheids treatment required as much 

 time as in the heartwood ; and on microscopical examination both heartwood 

 and sapwood were found to have the same appearance. In the radial ducts 

 of the specimens from Montana sapwood penetration was much greater than in 

 those from California. Immediately after pressure was applied oil flowed from 

 these ducts, and the entire sapwood, both springwood and summerwood, was 

 heavily treated within a few seconds. 



In the cylinder-treated sticks of the California tree both heartwood and sap- 

 wood had the same appearance, and while in both the summerwood appeared 

 to have the heavier absorptions, the springwood also was very heavily dis- 

 colored. The Montana tree, however, was not penetrated quickly in the heart 

 springwood, except in the case of certain pieces (Nos. 41-^6) which treated 

 like the sapwood. In these specimens the summerwood was treated throughout. 

 In case of the lighter absorptions the springwood was practically untreated, 

 but as the absorptions increased the proportion of springwood treated also 

 increased. 



In the California specimens longitudinal penetration averaged about 8 times 

 the radial and 30 times the tangential penetration. In the Montana specimens 

 the longitudinal penetration averaged about 4 times the radial and 50 times 

 the tangential penetrations. 



SPEUCE PINE ( PINUS GLABRA). 



The spruce-pine specimens were of extremely rapid growth. The summer- 

 wood was about one-half the width of the springwood. Resin ducts were very 

 numerous and large, especially in the summerwood. Radial ducts were few. 

 The sapwood was much lighter in weight than the heartwood. 



