182 The Botanical Gazette. [May, 
there are in P. cordata ‘‘peculiar starch cells” on each side of 
the fibro-vascular bundle. The ‘‘specialized cells,” as he fur- 
ther designates them, were noticed in the petiole and leaf- 
bundles of P. crassipes just without the xylem portion of the 
bundle on either side, also an abundance of grains was seen 
in the larger parenchyma cells of the sheath proper (see fig. 
4.). Also in P. cordata these cells were noted, with little 
starch or none in the larger cells surrounding. Sachs® says 
that ‘the reservoirs of reserve materials or organs of assimi- 
MUON no. are chiefly in that layer of parenchyma 
which immediately surrounds the vascular bundle.” This 
Sachs long ago introduced into physiology as the ‘‘endoder- 
mis” and called it the ‘‘starch-bearing layer.” As these 
‘specialized cells” are part of the parenchyma cells of the 
‘‘starch-bearing layer” of Sachs, one is hardly justified in des- 
ignating these cells ‘peculiar starch cells,” when their pres- 
ence is the rule in all bundles. In Heteranthera limosa starch 
is very abundant in stem, petiole, and leaf, particularly in the 
parenchyma bundle sheath and the loose cells immediately 
about the bundle on both sides of the xylem, also in the celis 
of the diaphragms. 
These conditions illustrate an important physiological fact, 
that the store-houses of food are near the highways, where tt 
is most easily accessible. The distribution of reserve food in 
: a F : r axes lac 
spindle-like shape (fig. 5.), with their longe ‘iia erted 
d into the 
f cal- 
this 
examined. In P. cordata, the sac attains a length ary’ 
than three times the thickness of the diaphragm. 
ee ee eee 
*Physiology, 358. 
1°Comparative Anatomy, 220, 
