148 SEEDS 



horse-radish root yields allyl isothiocyanate ; scurvy grass (Cochle- 

 aria officinalis, Linne) and nasturtium seed (Tropceolum ma jus, Linne), 

 isobutyl isothiocyanate (C 4 H 9 NCS) ; radish (Raphanus sativus, Linne) 

 and watercress (Nasturtium officinale, Linne), principally phenylethyl 

 isothiocyanate (C 8 H 9 NCS) ; and cress (Lepidium sativum, Linne), 

 benzyl isothiocyanate, (C 7 H 7 NCS). 



Black mustard seeds also contain about 29 per cent, of proteid 

 matter and yield from 4-2 to 5-7 per cent, of ash. Starch, which is 

 present in the unripe seed, is not found in any of the cells of the ripe 

 seed. 



Uses. Applied externally, black mustard acts as a rubefacient and 

 counter-irritant ; this effect is followed by loss of sensibility in the 

 part, and consequently relief from previous pain. Prolonged action 

 may result in vesication. Internally, mustard is used as a condiment, 

 and in full doses as an emetic. 



Varieties. Indian mustard (B. juncea, Hooker and Thorns) is widely cultivated 

 in Southern Russia and India ; the seeds resemble black mustard but are rather 

 larger and browner in colour ; the volatile oil is believed to contain about 40 per 

 cent, of allyl isothiocyanate, and 50 per cent, of crotonyl isothiocyanate, 

 C 4 H 7 NCS ; they are sometimes sold as black mustard seeds. 



WHITE MUSTARD SEEDS 



(Semina Sinapis Albae) 



Source, &C. Brassica alba, Boissier (N.O. Cruciferce), the white 

 mustard, is cultivated like the black mustard, which it closely resembles, 

 but not to so large an extent. It differs from the black mustard in 

 producing more or less horizontal hairy fruits, those of the black 

 mustard being erect, appressed, and smooth. Each fruit contains 

 from four to six seeds. 



Description. White mustard seeds are yellow in colour, nearly 

 spherical in shape and about 2 mm. in diameter. The seed-coat is 

 very minutely pitted, the pits being so small that the seed appears 

 smooth until examined with a lens. Internally the seed is yellow, 

 and the oily kernel consists, as that of the black mustard seed does, 

 of the two folded cotyledons embracing the small radicle ; it becomes 

 coated with mucilage when soaked in water, and can afterwards be 

 easily deprived of its seed-coats. 



White mustard seeds, either whole or powdered, are free from 

 pungent odour, even when triturated with water. They have, never- 

 theless, a pungent taste. 



The student should soak some white mustard seeds in water, remove 

 the seed-coats, and observe the cotyledons and radicle, noting that 

 the seed is exalbuminous ; he should also crush the seeds, moisten 



