324 BOTANICAL GAZETTE [APRIL 
5. From evidence derived from a consideration of primitive 
and conservative regions in Liriodendron, Magnolia, Paeonia, and 
Vitis, it may be concluded that the primitive type of vessel in the 
Angiosperms is pitted, and has been derived from the pitted 
tracheid as have the mechanical and longitudinal storage elements 
of the wood. 
This investigation has been carried on in the laboratories of 
plant morphology at Harvard University under the direction of 
Dr. E. C. Jerrrey. In conclusion I wish to express my thanks to 
him for the material supplied and for his invaluable aid throughout 
. the work. 
WELLESLEY COLLEGE 
LITERATURE CITED 
1, Battery, I. W., Anatomical characters in the evolution of Pinus. Amer. 
Nat. 44:284-293. 1910. 
2. Brown, F. B. G., Scalariform tanh a efeenee! feature in angiospermous 
secondary wood. Science N.S. 48:1 18. 
3. Jerrrey, E. C., Anatomy of woody faa University of Chicago Press. 
4, SOLEREDER, Hans, Systematic anatomy of the Dicotyledons. Trans. by 
Bers and Fritscu. Oxford. Clarendon Press. 190 
. THompson, W. P., Independent evolution of vessels in Guctales and Angio- 
sperms. Bor. Gaz. 65:8 
6. ———, Anatomy and relationships of the Gnetales. I. Ephedra. Ann. 
Rotany 26:1077-1104. I912 
EXPLANATION OF PLATES XVI-XX 
PLATE XVI 
Fic. 1.—Longitudinal radial section of bundle of rhizome of Pieris aquilina; 
Fic. 2.—End wall of vessel of Pieris aquilina in face view, reticulated type; 
Fic. 3.—End wall of vessel of Pteris aquilina in face view, scalariform type; 
Fic. 4.—Portion of vessel of Pteris aquilina, profile view; 166. 
Fic. 5.—Longitudinal radial section of young twig of Ephedra; X125. 
Fic. 6.—Longitudinal radial section of older twig of Ephedra; 250. 
Fic. 7.—Longitudinal radial section of stem of Gnetum Gnemon type; 62. 
Fic. 8.—Longitudinal radial section of stem of Gnetum Gnemon type; X 187- 
