22 
about the cells.* The cell cavity is quite uniform in breadth, grad- 
ually diminishing upwards, as in Fig. 14, or sometimes quite abrupt- 
ly, as in Fig. 15. In some cells the cavity plainly extends to the 
cuticle, though in others it cannot be traced so far. A number of 
folds run down into the lateral walls, rarely, however, obviously 
entering the cell cavity as in Phaseolus or Gymnocladus. 
The I-shaped support-cells (Fig. 16, II.) are similar to those 
of Gymnocladus, though the intercellular spaces and I-shaped 
cavities of the cells are frequently larger. The third evident layer 
(Fig. 16, III.) is made up of loose, thick-walled ce!ls with numer- 
ous intercellular spaces. The cells of the fourth layer are rather 
more compact, are elongated laterally and carry the brown 
pigment. 
THE SEA BEAN (Mucuna urens.)—The seed-coat of the sea 
bean is exceedingly hard, but is only composed of two well de- 
fined layers; a palisade layer, having a brownish color, and a 
layer of loose parenchyma, the cell walls of which are colored 
dark brown. 
In a surface view (Fig. 17) the palisade cells are five or six 
sided, with the characteristic foldings of Phaseolus and Gymno- 
cladus, excepting that the central portion is greatly enlarged. 
In most cases the folds terminate in the angles of the cells and are 
often slightly enlarged. In a cross section of the seed-coat (Fig. 
18,) the thickened cuticle of the palisade layer is well defined (a,) 
as is also the light line (Fig. 18, 6) which runs close under the ~ 
cuticle and is somewhat broader than in the calabar bean. In an 
isolated palisade cell (Figs. 19, 20 and 21) the cavity is seen to 
extend to the cuticle; it is much wider at the base than is the 
cell cavity of the calabar bean. At Fig 20, a, it is indistinct and 
small; it, however, gradually enlarges upwards until it reaches 
the cuticle, where it attains considerable breadth. The outline of | 
the cell cavity is irregular and wavy. The folds extending into 
the lateral walls are very variable; some are very short, as in Fig. . 
* According to A. Sempolowski, I. c., p. 26, Plate II., Fig. 16, the palisade cells of 
the seed-coats of Lupinus angustifolius, L. luteus., L. albus, L. hirsutus, L. pilosus, 
and L. Cruikshankii have, in the lower part ‘of the cell, what he has called 
_ pore-canals, in the form of the cross-striations which I have described in the 
- abar bean, The cross-striations of the calabar bean are plainly not pore-canals, 
