THE LEAF 167 
removed from the plant during the day time and viewed 
under a high power, the chlorophyll bodies, on treatment 
aos 
&, 0 
eee xl 
Fobv 
Fic. 223.— Transverse section through a leaf of beet: e, upper epidermis; e’, 
lower epidermis; st, stoma; a, air space; p, palisade cells; ¢, collecting cells; sch, 
spongy parenchyma; 7, 7, intercellular air spaces; Fbv, section of a vein (fibrovascu- 
lar bundle). : 
with iodine, will be seen to contain granules of starch which 
they are in the act of elaborating. The collecting cells, ¢, 
receive the assimilated product from the 
palisade cells and pass it on through the 
spongy parenchyma, sch, to the fibrovascular 
bundles. Notice how much more abundant 
the green matter is in the upper part of the 
leaf than in the lower; has this anything to 
do with the deeper color of the upper surfaces res 
of leaves? Notice the opening, st, in the rophyll bodies con- 
lower epidermis; do you recognize it? (See ee a 
Fig. 222.) It is a stoma, seen in vertical mation. Magnified 
section. Notice the intercellular air spaces, 7°° t™* 
z, 7, in the spongy parenchyma, and the much larger one, a, 
just behind the stoma. Why is this last so much larger? 
