20 
parenchyma. VI. A layer of star-shaped parenchyma-cells. 
The palisade cells are greatly elongated radially ; the lateral 
walls are thickened asin Phaseo/us, but more uniformly, because 
of the uniformity of the cell cavity (Figs. 8,9 and 10). In Figs. 7, 
8, 9 and 10 at 4, several prominent rounded points may be seen 
which refract light very strongly. This appearance is not affected 
when the cells are macerated in potash, or Schultze’s medium, 
or when allowed to decay, somewhat, in water. The cell cavity is 
slightly enlarged at the base (Figs. 7, 8, 9 and 10, at d@.), dimin- 
ishing in calibre upward to e, when it again begins to enlarge to 
the point 6. From ato the cuticle the cell cavity is faint and 
can only be definitely made out in stained sections.* 
The folds are from two to eight in number and vary greatly 
in their length and manner of joining the cell cavity. In Figs. 
8, 9 and 10 the refractive points are shown; they have the same 
peculiarity that the cell-cavity has. From @ to the cuticle (Figs. 
8, 9 and 10) the folds are very faint, and can only be distinctly 
seen after staining. In the lower portion of the palisade cells 
(Figs. 8 to 10) are several slight folds which generally arise 
gradually. After they have attained considerable breadth they 
begin to diminish in size and end as fine threads. Sometimes 
they are apparently disconnected from the cell cavity, asin Fig. 8, 
and in some cases they have more than one of these fine endings. 
There are two well-developed light lines on these cells,t a wide 
and a narrow one. The wide light line begins close under 
the cuticle, extends to the refractive points (Fig. 7, 2-4), and 
is lighter in its upper than in its lower portion. The narrow 
line (Fig. 7, c) is situated slightly above the central part of the 
palisade cells and has a much clearer definition than the 
broad line. The second layer is made up of I-shaped sup- 
port-cells, homologous with the crystal layer of Phaseolus, but 
having numerous intercellular spaces. The cavity of these 
cells is very narrow at the middle (Fig. 7, II., ), enlarging as it 
reaches the upper and lower cross-bar, thus giving to it also the 
shape of an I. The third layer differs remarkably from any of 
“The fluids used were methyt violet and chloriodide of zinc. 
tI shall speak of their behavior with micro-chemical tests in another connection, 
