SEEDS. 



133 



PLATE LVI1. 



FIG. 67. Powdered Black Mustard Seeds (x 240). 



am, Mucilaginous epidermis without distinct concentric striations. 



ap, Aleurone layer, isolated. 



AP, The same together with the membranous layer, cm. 



CO, Margin of cotyledon in transverse section, with epidermis, e'C'. 



ec, Epidermis of cotyledon, surface view. 



ra, Radicle. 



sc, Sclerenchymatous layer surface view ; the cells are brown and 

 exhibit the characteristic polygonal network. 



s'c', The same in profile, showing the characteristic thickenings. 

 v, Debris of raphe. 



