

SPICES AND CONDIMENTS. 171 



MUSTARD. 



Mustard of commerce is the seed, whole or ground, of several species 

 of the genus Brassica, cruciferous plants which grow wild and are cul- 

 tivated under very various conditions. The two common varieties are 

 the black or brown mustard, which has a very small seed and furnishes 

 the most kroma, and the white, which is two or three times as large, 

 often used in the whole condition in pickles and ground, either by itself 

 or ofteuer in mixture with the brown seed, for the purpose of obtaining 

 the desirable qualities of both. 



In the ground mustard is found only the interior of the seed and 

 small portions of the husks which have escaped the operation of bolt- 

 ing, which is always employed to remove the coarse fragments. The 

 presence of these particles from their characteristic structure enable 

 us to recognize the source from which the flour is derived and to detect 

 the use of the mustard hulls as adulterants of other food materials. The 

 husk of white mustard is represented, after a drawing by Schimper, in 

 Fig. 10. 



The outer colorless epidermis consists of angular plates or hexago- 

 nal tabular cells with a center of different brilliancy. They swell up 

 and become slimy in water and must therefore, be observed in glycer- 

 ine. At the best it requires some manipulation to see it well, and it is 

 far less prominent in the brown seed. The next coat, denominated the 

 subepidermal, is not prominent and can only be seen at all easily in the 

 white seed. 



The third layer is an important one. In it is found the coloring mat- 

 ter of the brown seed, and its absence is the cause of the lack of color 

 in the white variety. Fragments of this layer are common in ground 

 mustard. It is distinguished by the thick or colorless brown cell walls 

 and their irregular dotted appearance. Once examined it will be readily 

 recognized under other circumstances, as, for example, when the hull 

 is used as an adulterant of pepper. 



Between this layer and the next are some unimportant and difficultly 

 discernible cells carrying in the brown seed some color. 



Within these comes the important layer denominated the inner tunic 

 by Hassall and the plasma layer by Schimper. It separates readily 

 from the other parts of the husk and is often found by itself in the 

 ground mustard. As its contents are broken up by water or chloral 

 hydrate, glycerine or oil must be used as a mounting medium. The 

 cells of which the layer consists are large, and with their contents are 

 similar to the embryous envelope or false gluten cells of wheat, to 

 which they correspond. They are much alike in both white and brown 

 mustard. These structures are diagramatically represented in Fig. 7. 



From the character of the exterior layer and the lack of color in the 

 third layer, as well as minor differences which are not describable, but 

 will appear to the patient investigator, it is always possible to tell 



