Medical Officers of the Army of India.
33
however, be taking place, for, after the lapse of a few weeks, the under-surfaces
of the leaves, both old and new, become gradually coated with a thin, brownish
stratum due to universally distributed eruption of minute pustules containing
uredospores and teleutospores. There is in this crop not a trace of spermogo
-nia. Sections of the laminæ show them to be everywhere penetrated by
mycelial filaments. At points corresponding with the bases of the pustules, such
filaments are present in great abundance and become continuous with masses
of cells which, as in the case of those of the uredosporic fructification of the
previous crop, are situated in the intercellular spaces between the deeper por-
tions of the subepidermal cells of the host (Fig. 12, Plate II). From these
masses of cells teleutospores in large numbers, and a certain number of uredo
-spores, arise. The pustules are always of very small size, only yielding a small
number of spores each, but, as they are everywhere present, the quantities of
spores, and specially of teleutospores which they furnish, are enormous. The
uredospores resemble those of the previous crop, and, like them, have long stalks,
which pass up between the cells of the subepidermal tissue and give origin to
the spores beneath the epidermis, which is first elevated and stretched, and
finally ruptured, as they increase in size. The development of the teleutospores
is essentially similar to that of those of R. sessilis. As in that species, each
spore is the product of several distinct stems which unite terminally and develop
a mass of basal cells from which the true spore-cells are produced (Fig. 13,
Plate II). The number of basal cells and spore-cells always, however,
remains comparatively limited, and the basal cells do not give off any special
cystic protrusions. Perfectly fresh mature spores are, however, not devoid of
cystic appendages, the entire bodies of the basal cells becoming dilated and taking
the place of the special cysts. Each detached spore at this time is thus seated
on a very delicate cushion of very tenuous cysts, which in some cases carries a
short portion of the stalk attached to it inferiorly. The cysts are very perish
-able, and they never show the brilliant refraction of the fresh cysts in R. sessilis.
As in the case of the cysts of that species fine mycelioid radiant filaments, due
to persisting portions of the cell-walls, often form fringes around the base of the
spores after the cysts themselves have disappeared.
The teleutospores vary very greatly in size, due to the very different number
of constituent cells which is present in different instances. In some spores only
five cells are present, while others may contain as many as nineteen or twenty.
The spores never attain magnitudes equal to those of large teleutospores of
R. sessilis. On an average they have a diameter of about .0626 mm. and
a h e i g h t o f . 0 1 9 8 mm. T h e y a r e o f a d e e p g o l d e n b r o w n c o l o u r . T h e e p i s p o r e
over the upper-surface is thickly tuberculate (Fig. 5, Plate II), and the marginal
cells are also provided with a single row of large spines, situated, like the row
of tubercles around the teleutospores of R. sessilis, along the line where their
inferior and outer surfaces meet. The size of the individual spore cells varies
F