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visions but to the species as well. The results of this work appeared in 
1886 in the “Botanical Gazette,” XI, pp. 256-262 and 302-309. 
The object of their study was to determine whether the pines could 
be separated from one another by means of the structure of the foliage 
ABIES FRASERI. 
D Duets. M Mesophyll. 
B Bundle sheath. S Strength. cells. 
F Fibro-vas. bundle. E Epidermis. 
leaf. The material used by them was gathered from as large a range as 
possible and thus have the material grown under as many conditions as 
possible. Their determinative features were based upon the number of 
fibro-vascular bundles, the position and kind of strengthening cells, the 
position of the stomata, the number and position of the ducts, thickness 
