60 OrR—LEAF GLANDS OF DIOSCOREA MACROURA. 
The glands are the dark-coloured areas, the contrast being 
produced by the deeply- staining secretion, which fills the 
glandular ‘‘pockets.’’ It will be observed that only two of 
these glandular areas appear in the section, in place of the four 
or six referred to in the description of the external features of 
the acumen. ‘This reduction in number is accounted for by the 
process of fusion which has been shown to take place between 
the outer and inner glandular ridges, resulting in the formation 
of the two combined glands, which alone persist in the distal 
portion of the acumen. Each gland is an elongated ‘“‘ pocket”’ 
_in the mesophyll, which, in transverse section, has an extremely 
irregular aiiiae due to the frequent infolaiage of the wall- 
layers. Its truly convoluted character, however, can only be 
fully appreciated by following its course through a series of 
longitudinal sections. 
This ‘‘ pocket’? communicates with the upper surface of the 
acumen by way of the longitudinal slit, referred to above, the 
epithelium of which is epidermoid in character, and is strongly 
cuticularised, judging by its reaction to microchemical tests, 
and this property is shared, but to a less degree, by the cells 
which form the lining of the gland cavity itself. In the apical 
region of the acumen, from which this section was taken, the 
undulating character of the upper surface is not so pro- 
nounced as it is nearer the base, and the ducts, which, in the 
section, appear as narrow, winding canals, open ies into 
a shallow channel formed by the two marginal flanges of 
parenchyma. 
Internally, the opposing epithelial lavers of the duct diverge 
abruptly to form the roof of the gland cavity, turning upwards 
in their course until the upper limits of the gland are reached, 
and thus partially enclosing a patch of mesophyll, roughly semi- 
circular in outline, with a much-indented circumference due to 
frequent infolding of the limiting layer. From the extremities 
of the gland, the epithelium is continued downwards to form the 
curved floor of the crypta, from which the secretory tissue o* 
the gland is developed 
The cells which compose this superficial layer, with the 
possible exception of those which form the basal attachments of 
the secretory elements, have not only their outer, but also their 
lateral walls cuticularised, somewhat after the manner of an 
; _endodermis, while their inner walls remain unaltered. Some- 
he investigate. This distribution of the cutin in the cell-walls 
P athe obvious in sections stained with safranin or 
ia blue. 
