270 THE AMERICAN MONTHLY [Sept 



S. ALTISSIMUM, L. 



Slender, slightly curved pods, two to four inches long, 

 firm, cylindrical. Seeds light straw colored, one-half to 

 three-fourths line or less long ; oblong ornearly triangu- 

 lar. 



On the addition of water the cell-wall of outer seed 

 coat becomes mucilaginous. Outer epidermal layer 

 covered with cuticle, cells elongated, on the addition of 

 water, walls become mucilaginous and show stratification. 

 Cell-walls of second layer thick, light brown, followed by 

 endosperm of two layers of cells, first elongated, thick- 

 walled. 



Cells of embryo as in S. officinale, 



Lepidium virginicum, L. 



Pod orbicular or oval, a line and a half to one and three 

 fourths lines long, larger than L. apetalum, with a small 

 notch at the top, slightly margined above, often purple 

 tinged at maturity. Seeds pendulous, light brown, 

 minutely pitted, with a narrow winged margin, one line 

 long. The .caulicle runs lengthwise, on each side a 

 groove, marking the boundary between the caulicle and 

 cotyledons, the latter accumbent. On the addition of 

 water the outer-walls become mucilaginous. 



The seed coats consist of three well defined layers. 

 The outer or epidermal cells are tabulated, somewhat 

 compressed. The cuticle forms a continuous layer over 

 these. On the addition of water the epidermal cells 

 elongate and form a mucilaginous mass, showing strati- 

 fied layers. These are not difficult to make out when the 

 specimen is mounted in water. The cell cavity is very 

 much reduced, that portion of the cell- wall in contact 

 with the cell-cavity is difl"erentiated from the outer cell- 

 wall substance. Long continued addition of water causes 

 the cuticle to break and the exterior becomes very irreg- 

 ular. 



