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on the Genus Drimys . 
dicotyledonous type. If the resemblance to oak wood in general organiza- 
tion is of value, it is clear that Drimys has come from a comparatively 
primitive Ranalian type. Although the general structure of the woody 
tissues of the genus under discussion is primitive, the absence of vessels can- 
not apparently, in view of the present investigation, be so regarded. It 
seems quite clear that the ancestors of Drimys possessed vessels, and that 
these were of a type characterized by lateral scalariform pits and probably 
by scalariform perforations. The absence of perforations is merely a 
technical distinction between tracheides and vessels in the case of the 
Dicotyledon, and has no decisive evolutionary significance. No discussion 
of the evolutionary history in the case of vascular structures is complete 
unless the lateral as well as the end walls of the vessels are taken into 
consideration. 
Summary. 
i. The roots in Drimys , in particular D. color ata, as a consequence 
of injury develop peculiar tracheary structures. 
3. The structures in question are regarded as the abortive and rever- 
sionary return of vessels because of the resemblance of the sculpture 
of their lateral walls to that found in the vessels of the Magnoliaceae. 
3. These traumatically induced elements are characterized by the 
opposition and fusion of rows of pits, and in this respect are clearly distinct 
from ordinary tracheides. They, however, lack the perforations of normal 
vessels. 
4. In spite of the absence of perforations, they are apparently to be 
interpreted as a clear indication of the former presence of vessels in Drimys 
and similar forms among the Magnoliaceae. 
5. Drimys is a representative of the Magnoliaceae primitive in position, 
as evidenced by its ray structures and the character of its traumatically 
recalled vessel-like elements. 
DESCRIPTION OF PLATE VII. 
Illustrating Professor Jeffrey and Miss Cole’s paper on Drimys. 
PLATE VII. 
Fig. 1. Transverse section of wood of Drimys colorata , showing absence of vessels and broad and 
uniseriate rays, x 40. 
Fig. 2. Longitudinal tangential section of the wood of D. colorata. x 50. 
Fig. 3. Transverse section of wood of D. colorata. x 125. 
Fig. 4. Longitudinal radial section of wood of stem of D. colorata. x 125. 
Fig. 5. Longitudinal radial section of wood of stem of D. axillaris, x 125. 
Fig. 6. Longitudinal radial section of root wood of D. colorata. x 125. 
