150 Trans. Acad. Sci. of St. Louis. 



Medicago lupulina, L. 



PL VIII. f. 3-3b. PL XXIV. f. 2-2b. 



Testa and endosperm well developed, 245 fji in thickness on 

 sides. More than half of this thiclvness consists of endo- 

 sperm . 



Malpighian. Cells 40-42/^ in length. Cuticle slightly 

 irregular; underneath the cuticle a light-colored area with 

 conical projections, as in Melilotus., but somewhat more promi- 

 nent. With chlor-iodide of zinc this rapidly colors blue. It 

 corresponds to the mucilaginous " membrana interna" of 

 Mattirolo and Buscalioni, and, as shown by Schips, is chemi- 

 cally differentiated from the cuticle and remainder of the 

 cell-wall. The conical layer is highly refractive. The light 

 line occurs below the conical layer and colors blue soon after 

 the addition of chlor-iodide of zinc. The ceU-cavity is broad- 

 est at the base, gradually tapering upward. A large chroma- 

 tophore occurs at the base or near the middle of the cell-cav- 

 ity. In colored seed some pigment occurs in the cavity as 

 well as considerable amounts in the walls. Small pore-canals 

 occur in the upper part of the cell-waU. The ceU- walls color 

 blue more slowly with chlor-iodide of zinc than the cuticular- 

 ized layer. 



Osteosclerid. Cells broad at the base, with conspicuous 

 longitudinal pores; intercellular spaces below the Malpighian 

 cells triangular; walls colored brownish; cells containing 

 jDigment and tannin. 



Nutrient. This layer is much compressed, and differentiated 

 into two parts; cells elongated, rather thin-walled; those in 

 the lower portion carry a great deal of pigment, and are much 

 more compressed that the upper portion. 



Endosperm. The endosperm is of unequal development, 

 laterally as much as 150 // in thickness. Harz gives the thick- 

 ness as 250 p.. Cells of the aleurone layer rectangular, thick- 

 walled, and filled with fat and protein grains. This layer is 

 followed by reserve cellulose. The primary wall persists 

 when treated with weak solvents. The walls, except the 

 primary, color blue with chlor-iodide of zinc. The inner 

 portion of the endosperm consists of thick-walled, elongated 

 cells. 



