SINAPIS ALBA 279 



growth a distinct cleft or horseshoe-shaped fissure, occasional altered 

 and swollen grains from 0.060 to 0.090 mm. in diameter; tracheae 

 few, with simple pores, or reticulate, annular or spiral markings; 

 fragments of epidermal cells with thin brownish walls; sclerenchym- 

 atous fibers very few or wanting; sclerotic cells in D. Cucullaria 

 very characteristic, being irregular in outline, mostly elongated, 

 attaining a length of 0.750 mm. and a width of 0.100 mm., walls 

 heavily lignified and about 0.020 mm. in thickness, and porous, 

 occurring either isolated or in groups of from two to four: sclerotic 

 cells from the rhizome of D. canadensis, few, mostly isodiametric, 

 uniformly smaller than those of D. Cucullaria, the walls being 

 about 0.012 mm. in thickness and not distinctly irregular in outline; 

 rosette aggregates of calcium oxalate, from the portions of rhizome 

 of D. canadensis, few and 0.020 mm. in diameter. Newcomb. 



CRUCIFERjE, OR MUSTARD FAMILY 



The plants are mostly herbs, occasionally woody, and include 

 about 1500 species, which are widely distributed. The flowers 

 consist of 4 sepals, 4 petals, 6 tetradynamous stamens, and a single 

 compound pistil, becoming in fruit usually a 2-locular silique or 

 silicle. They are especially characterized by their colorless secretion 

 cells. These very closely resemble their neighboring cells, but in 

 the cortex and mesophyll are usually somewhat elongated. Their 

 exact location may be determined by the use of certain reagents. 

 They are stained by the anilin dyes; with solutions of orcin or orcein 

 and hydrochloric acid they are colored violet; with Millon's reagent, 

 consisting of' a solution of mercuric nitrate, the contents are pre- 

 cipitated and colored red. In alcoholic material the contents of the 

 secretion cells are precipitated and their position more readily 

 determined. Myrosin-secreting cells occur in nearly all of the 

 Cruciferas, with the exception of Capsella, Lepidium, Cakile and a 

 few others. In the leaves of the Cruciferae occur large water-storing 

 cells. These occur among tho epidermal cells and are readily dis- 

 tinguished by their greater size. The non-glandular hairs are 

 unicellular and of various characteristic shapes for the different 

 genera. Glandular hairs are seldom found, and calcium oxalate is 

 wanting. 



SINAPIS ALBA. Brassica Alba, White Mustard. The dried, 

 ripe seeds of Brassica (Sinapis) alba (Fam. Cruciferae), an annual 

 herb native of Europe and southwestern Asia, also naturalized and 

 extensively cultivated in many countries. The commercial supply 



