A ngiosperms Tetracentron , Trochodendron , and Drimys . 511 
Not only is there no direct structural evidence which might be con¬ 
sidered to indicate that these vessel-less Angiosperms are ‘ evascularized ’ 
forms, but there appears to be no physiological or ecological evidence for 
supposing that they are ‘degenerate’ Dicotyledons whose ancestors possessed 
true vessels in their secondary wood. 
The secondary xylem of Tetracentron and Trochodendron , which is 
entirely unlike the wood of the Coniferae, closely resembles that of certain 
of the Pteridophyta and older Gymnospermae. 
In conclusion, the writers wish to thank their botanical colleagues in 
Australasia, South America, England, and Japan for their courtesy in 
sending valuable material of Drimys > Tetracentron , and Trochodendron. To 
Dr. G. R. Wieland and Dr. E. W. Berry the writers are indebted for the 
opportunity of studying and photographing sections of Palaeozoic and Meso¬ 
zoic plants. 
Literature cited, 
1 . Eichler, A. W.: Bemerlcungen iiber die Structurdes Holzes von Drimys und Trochodendron , 
sowie iiber die systematische Stellung der letzteren Gattung. Flora, N.F., xxii, 1864, 
pp. 449 - 58 - 
2 . Groom, P.: Remarks on the Ecology of Coniferae. Ann. Bot., xxiv, 1910, pp. 241-69. 
3 . Groppler, R. : Vergleichende Anatomie des Holzes der Magnoliaceen. Bibliotheca Bot., vi, 
1894, pp. 1-49. 
4 . Harms, H.: Ueber die Stellung der Gattung Tetracentron Oliv. und die Familie der Trocho- 
dendraceen. Ber. Deut. Bot. Ges., xv, 1897, pp. 350-60. 
5. Jeffrey, E. C.: The History, Comparative Anatomy, and Evolution of the Araucarioxylon 
Type. Proc. Amer. Acad. Arts and Sci., xlviii, 1912, pp. 531—71. 
6. Jeffrey, E. C., and Cole, R. D.: Experimental Investigations on the Genus Drimys. Ann, 
Bot., xxx, 1916, pp. 359-68. 
7 . Leavitt, R. G.: A Vegetative Mutant, and the Principles of Homoeosis in Plants. Bot. 
Gaz.,xlvii, 1909, pp. 30-68. 
8. Mohl, H. von : Grundziige der Anatomie und Physiologie der vegetabilischen Zelle. Braun¬ 
schweig, 1851. 
9 . Solereder, H.: Systematische Anatomie der Dicotyledonen. Stuttgart, 1899. 
10 . Solms-Laubach, H., Graf zu: Ueber die in den Kalksteinen des Kulm von Glatzisch- 
Falkenberg in Schlesien enthaltenen Structur-bietenden Pflanzenreste. Bot. Zeit., li, 1893, 
pp. 197-210. 
11. Thompson, W. P., and Bailey, I. W. : Are Tetracentron , Trochodendron , and Drimys 
Specialized or Primitive Types? Mem. N. Y. Bot. Garden, vi, 1916, pp. 27-32. 
12 . Tieghem, Ph. Van : Sur les Dicotyledones du groupe des Homoxylees. Jour. Bot. (Paris), 
xiv, 1900, pp. 259, 330. 
13 . Wieland, G. R. : American Fossil Cycads, II. Washington, 1916. 
14 . Wilson, E. H., ex Sargent, C. S.: Plantae Wilsonianae, i, pp. 417-18. Cambridge, 1913. 
