142 BOTANICAL GAZETTE [AUGUST 
Harvard Forest for material of conifers, and to his colleagues, 
Professors T. W. Ricuarps, P. W. Bripcman, and Dr. W. T. 
Bovrie for helpful suggestions. 
Bussey INSTITUTION 
HARVARD UNIVERSITY 
“EXPLANATION OF PLATE I 
Fic. 1.—Pinus Strobus L.: tangential section showing penetration of 
carbon oe through bordered pits of freshly cut sap wood; 700. 
Fic. 2.—Pinus sp.: tangential section through bordered “ showing torus 
jammed into a a in secondary wall of left-hand tracheid; X 1000. 
Fic. 3.—Pinus sp.: tangential section through 2 “ae a pits showing 
usual valvelike action of tori; 1000, 
Fic. 4.— Sequoia sempervirens Endl.; tangential section showing penetra- 
tion of carbon suspension through Beetared pits; X 300. 
Fic. 5.—Dacrydium Franklinit Hood: radial section showing peculiar 
strap-shaped tori; X 700. 
Fic. 6.—Larix laricina (DuRoi) ‘Koch: radial section showing perforations 
in pit membranes; XX 520. 
Fic. 7.—Pinus palustris Mill.: tangential section showing heavy tar 
oil passing through bordered pits; X 600. ee 
