468 
Journal of Agricultural Research 
Vol. I, No. 6 
before black locust. The dogwood and persimmon sank in about 18 
hours, while the catalpa floated for 20 days, and one piece of black locust 
with a large percentage of heartwood remained floating for 46 days. 
SUMMARY 
The 143 specimens of hardwoods examined included 45 genera (94 
species), of which 24 contained tyloses. The 60 specimens of conifers 
examined included 13 genera (45 species), of which 1 contained tyloses. 
Of the 139 species examined, 56, belonging to 25 genera, contaired 
tyloses. 
Tyloses were found in the sapwood of all species in which they occurred 
in the heartwood. 
Well-developed tyloses were found in the outermost rings near the 
bark of 30 species of hardwoods. 
True tyloses occur in the wood tracheids of certain pines, principally 
of the white-pine group. 
Epithelial cells sometimes effect a partial or even complete tyloselike 
closing of the resin canals in Pinus, Larix, Picea, and Pseudotsuga. 
A considerable proportion of the vertical canals, even in the heart- 
wood of the pines, are fully or partly open. 
Tyloses act like a natural filler in the hardwoods. 
The woods in which tyloses are abundant as a rule are durable. 
Tyloses, because they are very impermeable to air, water, and creosote, 
reduce the penetrance of the woods in which they are strongly developed. 
The presence of tyloses in the vessels of a hardwood, however, does not 
prevent the penetrance of creosote into the other wood elements. 
LITERATURE CITED 
Bailey, I. W. 
1913. Preservative treatment of wood. In Forestry Quart., v. 11, no. 1, p. 
5-20, 2 pi. 
Bary, Anton de. 
1884. Comparative Anatomy of the Vegetative Organs of the Phanerogams 
and Ferns. Translated by F. O. Bower and D. H. Scott ... p. 170. 
Oxford. 
Boehm, Josee. 
1867. Ueber Function und Genesis der Zellen in den Gefassen des Holzes. In 
Sitzungsber. K. Akad. Wiss. [Vienna], Math. Naturw. Cl., Abt. 2, 
Bd. 55, p. 851-866, 2 pi. 
1877. Ueber den aufsteigenden Saftstrom und den Abschluss lebender Zellen 
gegen aussere Einwirkungen. In Bot. Ztg., Jahrg. 35, No. 7, p. 112-113. 
1879. Ueber die Function der vegetabilischen Gefasse. In Bot. Ztg., Jahrg. 
37, No. 15, p. 225-239; No. 16, p. 241-258. 
Chrysler, M. A. 
1908. Tyloses in tracheids of conifers. In New Phytol., v. 7, no. 8, p. 198-204, 
ph 5- 
Haberlandt, G. F. J. 
1884. Physiologische Pflanzenanatomie. p. 217. Leipzig. 
1887. Ueber die Beziehungen zwischen Function und Lage des Zellkemes bei 
den Pflanzen. p. 71-74. Jena. 
