386 
HEBER W. YOUNGKEN 
this region. Fibro vascular bundles of the bicollateral type are also to be 
noted. The most conspicuous elements of these regions are the spiral ducts 
which attain a breadth of 28.6 microns. 
Separating the receptacle from the carpellary portion of the fruit may 
be noticed a sharply delimited band of cells, three layers thick. Of these 
the outer layer and inner layer are comparatively clear; the middle layer 
is filled with dense protoplasmic contents. The innermost layer of cells of 
this region is the broadest, contains starch grains, and doubtless represents 
the epicarp of the ripened carpellary wall. 
Passing from this region toward the embryo, numerous layers of thin- 
walled cells are noted, of rounded or irregular outline, whose I'umina contain 
either protein or carbohydrate contents or both. This region constitutes 
the mesocarp. It is traversed by numerous bicollateral bundles. The 
endocarp consists of a layer of rather small tangentially elongated cells. 
Over that portion of this region which is unattached to the seed coat, the 
cells are larger and have very thick brownish walls. 
Seed 
The seed coat is composed of tangentially elongated cells, the outer walls 
of which are united firmly to a portion of the endocarp. 
Cotyledons 
The outer covering tissue or epidermis consists of a layer of cells which 
in surface view are polygonal, and rectangular when observed in transverse 
section. Many of the cells of this tissue possess starch grains. Branched 
stellate hairs and glandular hairs are scattered over this tissue. 
Beneath the epidermis is a spongy parenchyma composed of somewhat 
spheroidal to polygonal cells containing starch grains, which are mostly 
simple, spheroidal or plano-convex, rarely 2-3-compound. These have an 
ordinary range of 3 to 28 microns in diameter. Occasionally, somewhat 
elongated ovoid grains are seen which attain a length of 40 microns. 
Radicle 
This shows the usual structures typical of this portion of the cucur- 
bitaceous embryo. The cells of the cortex are rich in protoplasm, have 
prominent nuclei, but are entirely devoid of starch. 
Uses of the Chayote 
The fruits should be picked from vines when but two thirds or three 
fourths grown. They lose their delicate flavor and become tough if allowed 
to mature. They are then employed similarly to the squash. The vines, 
tuberous roots, and fruits may be used as fodder for stock. The woody 
stems furnish a fine fiber known to the French as paille de chouchon." 
Botanical Research Laboratory, 
Philadelphia College of Pharmacy 
