Winton — Anatomy of the Fruit of Cocos nucifera. 271 



branches may often be seen in cross sections of the trunk fiber 

 below the place of branching (fig. 5, a). 



a. Stegmata (figs. 5 and 6, ste). — As seen in surface view 

 these are circular or elliptical cells from '008 to -020 mm in diam- 

 eter, which extend in longitudinal rows over the surface of the 

 fibers. Longitudinal sections show that the cells are biconvex, 

 fitting into depressions in the bast-fibers, and that the outer 

 walls are exceedingly thin, while the inner and side walls are 

 strongly thickened, thus bringing the cell cavity near the outer 

 surface. Inclosed in each cell and filling it almost completely, 

 is a silicious body, from "006 to , 012 mm in diameter, with wart- 

 like protuberances on the surface which fit into corresponding 

 depressions in the cell walls (fig. 7). That they are composed 



Fig. 6. Longitudinal section of a large (mesocarp) fiber of the cocoanut. ste, 

 stegmata ; Si, silicious body ; /, bast fibers ; t, tracheids with small pits ; t', trache- 

 ids with large pits : sp, spiral trachea ; r, reticulated trachea ; sc, scalariform 

 trachea; s, sieve tube; c and c', cambiform cells, x 300. 



of silica is demonstrated by their incombustibility, their insolu- 

 bility in hydrochloric and nitric acids and their complete solu- 

 bility in hydrofluoric acid. Their appearance is particularly 

 striking in tangential sections which 

 have been heated on a cover glass 

 until thoroughly carbonized and 



finally treated with hydrochloric acid f^i^^JT ^J^ 4 " 

 on the slide. The heating should be 



performed at dull redness, since at a Fig. 7. Silicious bodies from 



higher temperature the bodies lose the stegmata of cocoanut fiber. 



.1 • i f • , • x 1500. 



their characteristic appearance. 



Wiesner* refers to these stegmata as " bast parenchyma," and 

 from his description it would appear that he considered them 



* Loc. cit , pp. 436-438. 



