146 



SEEDS 



and although the dry seeds are almost inodorous they develop, when 

 moistened with water, a volatile substance of extreme pungency that 

 rapidly attacks both the nostrils and the eyes. This volatile substance 

 is not, however, developed if the seeds have been previously thrown 

 into boiling water. 



The student should observe : , 



(a) The minute size and spherical shape, 



(b) The pitted surface, 



(c) The incumbent and folded cotyledons, 



(d) The pungent taste ; 



FIG. 85. Black Mustard seed. A, entire seed, magnified 3 diam. 

 B, transverse section, magnified 65 diam. : 4, 4, the two 

 cotyledons ; 5, the radicle. C, portion of the same, further 

 enlarged : ff, epidermis containing mucilage. (Berg.) 



and should compare these seeds with colchicum seeds, which are 

 larger, rougher, and harder than black mustard, and have a bitter, 

 not pungent, taste. 



Constituents. Black mustard seeds contain in the kernels about 

 27 per cent, of fixed oil (compare Expressed Oil of Mustard) which 

 can be extracted by crushing and pressing the seed. In the seed- 

 coal (in the cells of the epidermis) there is mucilage, which dissolves 

 when the seeds are soaked in water. The seeds contain, further, a 

 small quantity of acid sinapine sulphate (compare p. 149), and two 

 substances, sinigrin (about 4 per cent.) and an enzyme, myrosin, which, 

 by interaction in the presence of water, yield the volatile pungent 

 body previously referred to ; the latter is not a constituent of the 

 seed, but is produced from two of its constituents under certain 

 conditions. The assertion that black mustard seeds do not contain 



