202 PLANT ANATOMY. 
The function of the isolated bast-cells and stone-cells, for 
example in the Cinchona barks (Figs. 117, 145), in the Pome- 
granate-root (Berg’s ‘‘ Atlas,” plate XL.), Aconite root (Fig. 121), 
Simaruba, Coto bark (Fig. 118), Cort. Guaiaci (Fig. 105), 
Stipites Duleamare (Fig. 144), and Oak-bark is also still in 
doubt. Such cells, however, by the form of their transverse sec- 
tions and their arrangement, present very useful points of dis- 
crimination in the characteristics of many drugs (Cinchona'). 
Fia. 119.—Transverse section of a rootlet of Rhizoma Veratri. cc, epiblema (p. 177); 
m, fundamental tissue, only partly represented inthe drawing; 6, needle-shaped crystals; 
kk, nucleus-sheath,. : 
The nucleus sheath, vascular-bundle sheath or protective 
sheath (endodermis *), which occurs in the root formations of 
‘Compare also in this connection, Koch, ** Beitrage zur Anatomie 
der Gattung Cinchona,” 8vo, pp. 35, 2 plates. Freiburg dissertation, 
1884, especially page 20. 
* Evéov within, and 5épyaskin. Compare Schendener, ‘‘ Die Schutz- 
imme und ihre Verstirkungen,” Abhandl. der Berliner Akademie, 
