368 MR. H. M. CHIBBER ON THE MORPHOLOGY 
blasts or spicular cells in the mesophyll of many plants, e. y. those of 
Simaruba *. | 
Lower Epidermis (Pl. 18. fig. 14).—This differs from the upper epidermis 
in the following points. Tt, together with the hypoderma, can be peeled off 
by a simple aet of tearing the leaf in an oblique fashion. The peculiar 
small-celled patehes are absent ; the hypodermal layer is only one cell thick : 
stomata are present ; and, finally, the hairy covering consists of hairs of 
three types. These are the hydathodes, pearl-glands, and unicellular or 
uniseriate clothing-hairs. The hydathodes are precisely the same as those on 
the upper surface. The pearl-glands appear only temporarily and irregularly. 
In plants grown in the groves they are to be found on only some of the 
leaves, and that too in small groups here and there, They appear in greater 
profusion on leaves that have been plucked and kept moist for some days. 
As many as three hundred were eounted on one such leaf. These glands 
form large glistening spheres varying from one-half to one and a half mm. in 
diameter. They are filled with proteid and fatty substances. They are readily 
detachable, whether they are fully developed or immature. They are regarded 
ах food-bodies T, corresponding biologically to those on the tips of the leaflets 
of Acacia cornigera. The clothing-hairs are restricted to the veins. They 
are of the same character as those on the petiole and the young stem. 
They will be fully described later on. 
The epidermal cells are about the same length as in the upper epidermis, 
but the breadth is somewhat reduced, so that, instead of looking squarish, 
they have, generally speaking, an oblong shape (Pl. 18. fig. 14). The height 
is the same as in the case of the upper epidermis. The dimensions of a typical 
cell may be put down as 45 by 24 by 15. The lateral walls are straight or 
slightly curved, but never sinuate. The curve is very pronounced in the case 
of the accessory cells round a stoma. 
The stomata are more or less uniformly distributed. They number about 
five to six thousand per square centimetre. They have not any definite 
direction with reference to the leaf, nor is there any regular distance 
between them. Two of them may abut against each other, forming twin 
stomata, or a whole square measuring 300 р either way may not have a 
single stoma within it. The guard-cells are invariably surrounded by a 
circle of subsidiary cells $ ; their number is generally four. Often an 
additional or outer cirele of such cells is observed. The inner ring of 
* Solereder, Syst. Anat. Dicot., Engl. Trans. p. 183; also compare the following: * In 
Javanese rain-forests, according to Haberlandt, several species, including Gonvcarium 
pyriforme and Anamirta Cocculus, contain in their collenehyma mechanical cells, precisaly 
as do certain xerophytes" (Warming, (Ecol. PL, Engl. ed. p. 844). 
t Solereder, Z. c. p. 690. 
f The presence of a peripheral water-tissue entails the formation of accessory cells in 
connection with the stomata, according to Benecke (see Warming, l c. p. 125). 
