CRUDE DRUGS. 429 



employed, turmeric is also added to bring up the color, which latter 

 may be detected by means of the microscope (Fig. 290) and by its 

 becoming deep red with sulphuric acid and blue with iodine. 



Allied Plants. The seed of Tumip {Brassica campesiris) 

 is supposed to be the white mustard of Sanscrit writers. 



SINAPIS NIGRA. BLACK MUSTARD. The dried, ripe 

 seeds of Brassica nigra (Fam. Cruciferse), an annual occurring 

 much the same as Sinapis alba (p. 283). 



Description. Campylotropous, ellipsoidal or irregularly 

 spherical, i to 1.5 mm. in diameter; externally brownish-red, 

 seed-coat membranaceous, finely pitted, hilum whitish, forming a 

 conical projection, micropyle occurring as a slight depression ; 

 without a reserve layer, hypocotyl curved, cotyledons condupli- 

 cate ; inodorous ; taste pungent and acrid. 



Inner Structure. See Fig. 295. 



Constituents. Black mustard contains the same constit- 

 uents as white mustard, save that it contains more fixed oil (30 

 to 35 per cent) ; less of the ferment, myrosin ; and the sinalbin is 

 replaced by the glucoside, sinigrin (potassium myronate), which is 

 present to the extent of about i per cent, and yields on interaction 

 with the myrosin a light yellowish volatile oil (allyl isosulpho- 

 cyanide or volatile oil of mustard), which has an acrid, burning 

 taste, pungent odor, and also affects the eyes. In the reaction 

 there is also formed glucose and potassium acid sulphate. 



Allied Products. Of the seeds of the other Cruciferse which 

 somewhat resemble black mustard, the following may be men- 

 tioned : The seeds of Field mustard or Sinapis arvensis, which are 

 almost black and perfectly smooth : the seeds of Sarepta mustard, 

 (Brassica Bcsscriana), which are larger and distinctly reticulate; 

 Rape or colza seeds (Brassica Napits), which-are larger, not retic- 

 ulate and of a bluish-black color ; Turnip seeds yielded by Bras- 

 sica cauipcstris, which are somewhat larger but less acrid, and are 

 used in India in place of black mustard ; and Brassica juncea, 

 which is cultivated in tropical Asia for the same purpose. 



PEPO. PUMPKIN SEED. The ripe seeds of Cucurbita 

 Pcpo (Fam. Cucurbitacese) , a procumbent herb native of tropical 

 America and possibly tropical Asia, and long cultivated in tropical 

 and temperate zones (p. 387). 



