Ma*. 25, 1914 Tyloses in American Woods 465 



was not entirely due to the presence of tyloses, but the fact that the 

 creosote did not penetrate the tylose-filled vessels is significant. 



In a piece of desert willow (Chilopsis linearis), 4 by 1% by 2 inches, 

 treated with carbolineum, no penetration was visible in the heartwood 

 except about one thirty-second of an inch near the surface. In the 

 sapwood, however, where, as shown in Table I, the large vessels of the 

 two outer growth rings are without tyloses, the dark discoloration of the 

 preservative was clearly visible following the lines of these open vessels. 



Sapwood in general absorbs creosote much more easily than heartwood. 

 The supposed absence of tyloses in this region of the tree has previously 

 been regarded as one reason for this fact. As soon, therefore, as it was 

 satisfactorily determined that tyloses were unmistakably present in the 

 sapwood, special experiments were undertaken to discover what effect 

 they had on the absorption of the creosote. A piece of white oak was 

 given a commercial treatment at the same time and under the same con- 

 ditions as the black locust. The sapwood absorbed the oil fully, but the 

 penetration stopped abruptly at the line of color demarkation between 

 the sapwood and heartwood. (PI. UX, fig. 2 , B.) To the eye the heart- 

 wood, except for a surface coating, was absolutely untreated. The ves- 

 sels in both the sapwood and heartwood of this piece were filled with 

 strongly developed tyloses. Microscopic examination showed that the 

 tyloses in the vessels of the treated sapwood were entirely uncolored and 

 exactly like those in the vessels of the heart which was untreated through- 

 out. The tyloses had then effectually kept the creosote out of the ves- 

 sels, although there had been a full treatment of the wood fibers of the 

 sapwood. This shows that a considerable quantity of the preservative 

 was absorbed in spite of the fact that the presence of tyloses kept the 

 creosote out of the vessels. Hence, tyloses of themselves need not be 

 regarded as preventing the possibility of treating this species, at least in 

 the sapwood. 



A piece of oven-dried hickory, 2 % by 2 ]/* by 14 inches, made up of both 

 heartwood and sapwood, was treated at the same time and under the 

 same conditions as the oak and locust, and showed a thoroughly good 

 penetration throughout. (PI. UX, fig. 2,C.) Nevertheless, when the 

 wood was split, the tyloses, which were abundantly developed in the 

 vessels of both the sapwood and heartwood, were white and unstained by 

 the creosote, showing a marked contrast to the dark-brown fibers of the 

 surrounding treated wood. (PI. 1,11, fig. i.) 



The preliminary observations just described concerning the penetra- 

 tion of creosote were based on results of treatments made on single speci- 

 mens of the species studied and were regarded rather as valuable indica- 

 tions than as conclusive evidence. To check them with other results, 

 the treatments with creosote were repeated on other specimens of the 

 woods previously used and more specimens of another species con- 

 taining many tyloses. First, a piece of hickory taken from miscella- 

 neous material was given a high-pressure treatment with creosote. 



