RESISTANCE OF CONIFERS TO CREOSOTE INJECTION. 33 



ducts were usually filled with creosote, from which isolated spring tracheids 

 were frequently treated. 



In the sapwood the resin ducts were always thoroughly penetrated by creo- 

 sote. The summerwood was very heavily treated, and the springwood was 

 evenly stained to a color much darker than the untreated wood, although 

 creosote was not actually visible as such. Medullary rays were treated to 

 about the same extent as the springwood. 



In the cylinder the deepest penetrations and heaviest absorptions of the 

 heart were in the summerwood. Here the treated wood was usuaUy very 

 dark, except in the farthest limits of summerwood penetration, where the 

 color shaded so gradually to that of the natural wood that no line between 

 treated and untreated wood could be detected. While more difficult to treat 

 than summerwood, the springwood did not offer great resistance to penetra- 

 tion. Certain zones of springwood were often found that seemed to be filled 

 with an oil much lighter in color than that in the adjacent summerwood. 

 This may have been resin or creosote in which resin was dissolved. These 

 zones were located between heavily treated summerwood bands ; they were 

 usually very close to resin ducts and were found only in the more heavily 

 treated sections of the wood. 



In sapwood the summerwood was in every case very heavily treated. Spring- 

 wood was erratic in its absorption, some portions being black, others being only 

 slightly discolored. 



In general longleaf pine was found to be erratic in its penetrance and 

 absorption of creosote. The sapwood was very easily penetrated and absorbed 

 much oil without the aid of pressure. Merely dipping the sapwood was suffi- 

 cient to penetrate it completely and to secure absorptions almost as heavy as 

 those under the heaviest pressures. In heartwood the average longitudinal 

 penetration was about 26 times the average radial and 100 times the average 

 tangential penetrations. 



SHORTLEAF PINE (PINUS ECHINATA). 



The growth rings of shortleaf pine were broad, with summerwood which 

 often exceeded the springwood in thickness. Resin cells were never present. 

 Resin passages were large, numerous, scattering, and contained tyloses. Ray 

 ducts were also numerous. 



The average oven-dry weight per cubic foot of five heart specimens was 39 

 pounds, and of the five sap specimens, 31.8 pounds. 



In the heart the summerwood was treated more thoroughly than the spring- 

 wood, but penetration even in the summerwood was very difficult and took 

 place only around the resin ducts. Very frequently penetration failed to occur 

 in all of the summerwood tracheids, and often it occurred in only three or 

 four of them, and these separated from one another. These tracheids were 

 apparently reached from the medullary rays, which, in turn, were reached 

 either from other longitudinal tracheids or from resin ducts. The medullary 

 rays were frequently penetrated in one or more tracheids, and they may play 

 an important part in the treatment of this species. 



The heartwood in this species was one of the most impenetrable of the heart- 

 wood in any of the species tested; its longitudinal penetration was only 2.75 

 inches. In absorption shortleaf compares very favorably with other southern 

 pines. All of these species were variable in the heartwood, and it is probable 

 that if sufficient tests were made the penetration of shortleaf pine would show 

 results similar to longleaf pine. 



