MICROSCOPICAL EXAMINATION. 83 



CORN COCKLE. 



Agrostcmma gitJiago L. 



These seeds are crudely tetragonal in form and about 2.5 mm in 

 diameter, of a dull deep-brown or black color, and are covered with 

 a prominent papilla-like surface. 



The papillae are seen under the microscope to be provided with a 

 projection from each of the epidermal cells. (Plate IV, fig. 3.) The 

 cells are very characteristic, have sinuous outlines, and interlock with 

 adjacent cells. Beside the large papillae there are on the surface of 

 the cells fine warty processes, readily seen under a magnification 

 of 100. 



BOUNCING BET. 

 Saponaria ojficinalis L. 



These seeds are disk shaped somewhat like the lima bean, a dull, 

 deep black color, and are about 2 mm in diameter. With a hand lens 

 they are seen to have a papilla-like surface. 



The seed coats resemble, in some respects, Silene nocti flora L. in 

 the shape of the epidermal cells, but without the papilla-like projec- 

 tions or fine warty points (Plate IV, fig. 5), and the outlines of the 

 cells are not as prominent. 



NIGHT-FLOWERING CATCHFLY., 



Silene noctiflora L. 



These seeds are somewhat like tiny peas or shortened beans of 

 about 1 mm diameter and of a dull gray color. 



The seed coats of this species are highly characteristic (Plate IV, 

 fig. 6), each cell having a saw-toothed outline interlocking \rith its 

 neighbor. The middle lamella, constituting the bounding area, is 

 highly refractive toward light. In the center of each cell is a dark 

 portion produced by a protuberance forming a papilla-like roughness 

 on the surface of the seed; between these large points are fine warty 

 points, which, under the microscope, give it a slightly roughened 

 appearance. 



CURLED DOCK. 



Rumex crispus L. 



These seeds are the shape of buckwheat seeds, having three faces 

 and pointed at both ends, though more obtusely at the base. In 

 length they vary from 1.5 to 2 mm and are of a shiny brown color. 



In the coats of this seed the cells have strongly sinuous outlines. 

 (Plate VI, fig. 6.) The indentations are frequently half as great as 

 the small diameter of the cells. Difficulty is sometimes experienced 

 in sufficiently clearing these seed coats to enable one to see the mark- 

 ings well. 



