234 BOTANICAL GAZETTE [MARCH 
LITERATURE CITED 
1. BatLey, I. W., Reversionary characters of traumatic oak woods. Bor. 
GAZ. 50:374-380. IQIO. 
2. Eames, A. J., On the origin of the broad ray in Quercus. Bor. Gaz. 
49:161-167. IgIo. 
3. HotpEeN, R., Ray tracheids in Coniferales. Bor. Gaz. 55:55-66. 1913. 
4. JEFFREY, E. C., The comparative anatomy and phylogeny of the Coni- 
— Part re The genus Sequoia. Mem. Bos. Soc. Nat. Hist., Nov., 
I 
“ . Ibid., Part IJ. The Abietineae. Mem. Bos. Soc. Nat. Hist., Jan., 
1905. 
, Traumatic ray-tracheids in Cunninghamia sinensis. Ann, Botany 
22: Rees 1908. 
Te , The anatomy of woody plants. University of Chicago Press. 1917. 
8. THOMPSON, W. P., Ray tracheids in Abies. Bor. Gaz. 53:331-338. 1912. 
EXPLANATION OF PLATES XII-XV 
PLATE XII 
Fic. 1.—Transverse section of normal stem wood of Betula nigra, showing 
diffuse rays. 
Fic. 2.—Tangential view of same. 
Fic. 3.—Transverse section of normal stem of Quercus rubra, showing 
compound ray. 
Fic. 4.—Longitudinal section of same, showing compound ray in tangential 
aspect. 
Fic. 5.—Transverse view of wounded stem of Betula alba. 
Fic. 6.—Transverse section of wounded stem of Quercus rubra. 
PLATE XIlIl 
Fic. 7.—Transverse section of root of Betula nigra. 
Fic. 8.—Part of same more highly magnified to show aggregate ray. 
Fic. 9.—Transverse section through nodal region of B. nigra, showing 
one of leaf traces. 
Fic. 10.—Transverse section of seedling stem of B. alba. 
-FIc. 11.—Transverse section of reproductive axis of B. alba. 
Fic. 12.—Part of same more highly magnified. 
PLATE. XIV 
Fic, 13.—Transverse section of wounded stem of Betula alba. 
Fic. 14.—Tangential section through region opposite wound in stem of 
Fic. 15, art"of same more highly magnified to show aggregate character 
