Origin of Wood Parenchyma . 77 
gressive differentiation and diffusion through the ring was intimately related 
to the progressive refrigeration of the later Mesozoic. 
From the Comanchean deposits of Texas have recently been obtained 
two woods of Araucarian affinities which exhibit the incipient stages of 
tracheide septation demanded by the theory. These have been placed in 
a new genus, Telephragmoxylon. 
In conclusion, the writer expresses his indebtedness to Professor E. C. 
Jeffrey for assistance in the photographic work and for permission to use 
Text-figs, i, 2, and 3. 
Department of Botany, 
Mass. Agricultural College, 
Amherst, Mass. 
Literature cited. 
Jeffrey, E. C. : The Anatomy of Woody Plants. Chicago, 1917. 
Holden, Ruth r Contributions to the Anatomy of Mesozoic Conifers, No. 1. Annals of Botany, 
vol. xxvii, pp. 533-45, Pis. XXXIX and XL, 1913. 
EXPLANATION OF PLATE III. 
Illustrating Mr. R. E. Torrey’s paper on Telephragmoxylon and the Origin of Wood Parenchyma. 
Fig. 1. Radial section of the wood of Telephragmoxylon brachypkylloides , showing the charac- 
teristic ray and tracheide pitting. 
Fig. 2. Cross-section of the same, showing the Brachyoxyloid traumatic resin canals. 
Fig. 3. Cross-section of the same, showing the horizontal and pitted walls of the short tracheides. 
Fig. 4. Tangential section of the wood, exhibiting the septated tracheides at the end of the annual 
ring. 
Fig. 5. Detail of the last under higher magnification. 
Fig. 6. Cross-section of the wood of Picea sp. to show the position of the wood parenchyma on 
the face of the summer wood. 
