388 THE MICROSCOPE AND ITS REVELATIONS. 



Pyrola, Saxifraga. 1 The seeds of Umbelliferous plants generally are 

 remarkable for the peculiar vittce, or receptacles for essential oil, which 

 are found in their coats. Various points of interest respecting the 

 structure of the testa* or envelopes of seeds, such as the fibre-cells of Cobcea 

 and Collomia, the stellate cells of the Star-Anise, and the densely-conso- 

 lidated tissue of the 'shells' of the Coquilla-nut, Cocoa-nut, etc., 

 having been already noticed, we cannot here stop to do more than advert 

 to the peculiarity of the constitution of the husk of the Corn-grains. In 

 these, as in other Grasses, the ovary itself continues to envelop the seed, 

 giving a covering to it that surrounds its own testa, and closely adheres 

 to it. The ' bran ' detached in grinding consists not only of these two 

 coats, but also (as the Microscope reveals) of an outer layer of the grain 

 itself, formed of hexagonal cells disposed with great regularity. As these 

 are filled with gluten, the removal of this layer takes away one of the 

 most nutritious parts of the grain; and it is most desirable, therefore, 

 that only the two outer indigestible coats should be detached by the 

 * decorticating ' process devised for the purpose. The hexagonal cell-layer 

 is so little altered by a high temperature, as still to be readily distinguish- 

 able when the grain has been ground after roasting, thus enabling the 

 Microscopist to detect even a small admixture of roasted Corn with Cof- 

 fee or Chicory, without the least difficulty. 2 



1 These lists have been chiefly derived from the " Micrographic Dictionary." 



2 In a case in which the Author was called upon to make such an investigation, 

 he found as many as thirty distinctly-recognizable fragments of this cellular en- 

 velope, in a single grain of a mixture consisting of Chicory with only 5 per cent- 

 of roasted Corn. 



