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of the walls of the bundle sheath, and the number of leaves in a fasicle. 
With these characters, which appeared to be. permanent ones, a system of 
classification was formulated which was very useful in connection with 
the classification based upon external features. 
Since this time comparatively little, if any, work has been done upon 
ABIES SUBALPINA. 
D Duets. M Mesophyll. 
B Bundle sheath. ~ E Epidermis. 
F Fibro-vas. bundle. S Strength. cells. 
the Coniferae in this line. It was with this same end in view that the 
study of the generze Abies and Picea was taken up. The object here, as 
in the case of the Pinus, was to work out the characteristic features of 
the species of the two gener and find their determinative value. 
The material used was obtained of C. S. Sargent of the Arnold Ar- 
