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A TEXT-BOOK OF BOTANY. 



A B 



a/ 



FIG. no. A few illustrations showing the practical value of the study of calcium 

 oxalate: A, digitalis, without any calcium oxalate; B, hyoscyamus in which monoclinic 

 prisms predominate; C, belladonna, characterized chiefly by sphenoidal micro-crystals as 

 well as occasional prisms; D, stramonium, having rosette aggregates in addition to prisms 

 which are found in the petioles and stems and sphenoidal micro-crystals, which are abundant 

 in the root. a, upper epidermis; b, lower epidermis; c, non-glandular hairs (which in stra- 

 monium art tuberculate) ; d, glandular hairs; e, calcium oxalate crystals; f, fragments of 

 xylem showing tracheae with bordered pores (s), reticulate markings (r), simple pores (p), 

 spiral thickening (1), and wood fibers (w); g, bast fibers, which, together with wood fibers, 

 are wanting in digitalis. 





