208 THE AMERICAN MONTHLY [June 



the cell walls expand and after it has been moist for a 

 considerable time the cuticle breaks. Stratification is 

 very evident on the addition of water. The second layer 

 consists of rather thin walled parenchyma. The cells of 

 this layer differ greatly with reference to their size, being 

 scarcely at all developed in places, in others nearly as 

 large as the cells of the outer layer. 



The third layer consists of thick walled parenchyma 

 cells, densely packed, radially elongated, thick walled, 

 sides present a cone- shaped appearance. Underneath 

 this is a layer of thick-walled parenchyma cells which 

 contain some coloring matter. The endosperm follows 

 this layer. The first layer consists of thick walled cells, 

 densely packed with albuminous matter. The remaining 

 cells vary in number, much elongated, thick walled with 

 a small cavity ; these cells extend down between the 

 contiguous portions of the cotyledon or caulicle. 



The Embryo: — The cells of the first layer surrounding 

 the cotyledon or caulicle are smaller, filled with fat and 

 protein grains. The remaining cells are larger also filled 

 with fat and protein grains. The central part of the 

 caulicle shows a differentiation of the embryonic vascular 

 portion, consisting of small cells. 



Brassica sinapistrum, Boiss. 



Pods one to two inches long, the seed-bearing portion 

 somewhat torose and nerved, ascending, erect or some- 

 times appressed, tapering, prominently three to thirteen 

 seeded, and tipped with the globular stigma, the upper 

 one third to three fourths of an inch forming the ])eak, 

 often with a seed. Seed globular, one line in diameter, 

 brownish black, reticulated, the areas larger than in B. 

 nigra, grayish when the seeds have been moistened, 

 darker than B. nigra. When examined under the micro- 

 scope with alcohol, the outer layer oicell.s is compressed, 

 tabular, stratification not evident, cuticle well developed 

 and forms a continuous layer over the outer cells ; ou the 



