Medical Officers of the Army of India.
31
forcing the cuticle in front of them as they elongate. The peripheral ones are
considerably longer than the central ones and ultimately acquire a brownish
colour. They converge around the central ones and form a definite bounding
stratum. Oval spermatia are developed from the tips of the shorter central fil
-aments and accumulate in masses until, on the rupture of the cuticle and the se
- p a r a t i o n o f t h e a p i c e s o f t h e f i l a m e n t s o f t h e b o u n d i n g s t r a t u m , t h e y a r e e n a b l e d t o
escape in masses upon the surfaces of the leaves (Fig. 10, Plate II).
The spermogonia are somewhat smaller than those of R. sessilis, having an
average diameter of 0766 and a height of 0255 mm. The spermatia, on the
other hand, are larger than in the other species, giving diameters of 3 x
Another feature distinguishing the spermogonial fructification of R. stictica
from that of R. sessilisl i e s i n t h e n a t u r e o f t h e b a s e s o f t h e s p e r m o g o n i a .
The spermogonial beds of small-celled tissue are not so sharply defined and
limited to a sub-cuticular site as those of R. sessilis are, as the amount of fungal
tissue around the epidermal cells is so great, in many cases, as to displace and
conceal the latter very considerably. In some cases the displaced cells appear
to contain complex haustoria, and in others, especially in the areas intervening
between the bases of neighbouring spermogonia, they seem to be aborted, dis
- c o l o u r e d , a n d s h r u n k e n . I n m a n y p l a c e s t h e e p i d e r m a l t i s s u e a p p e a r s t o b e
entirely replaced by the masses of small-celled ,fungal tissue, which thus come to
rest directly on the pallisade cells when related to the upper surface of the
lamina. When this is the case the pallisade cells are often greatly malformed,
being enlarged, rounded, and seemingly occupied by haustoria.
The uredosporic fructification begins to make its appearance very shortly
after the spermogonial one. The patches are at first small and distinctly annu
lar, consisting of elongated, often confluent pustules, surrounding the spermogonial
areas (Fig. 11, Plate II). They afterwards come to vary greatly in size and may
become irregular in outline. The definite annular arrangement is soon obscured
as the masses of spores fall off and accumulate within and around the spermo-
gonial areas. The size attained by some patches is very considerable. One
which was measured gave diameters of 3 .5 x 2 . 25 mm. The pustules are
developed much less conspicuously around the spermogonial areas of the upper
surfaces of the leaves than around those of the lower ones. In many cases,
indeed, they are entirely absent, and when present they never form large groups,
but merely form a single, often imperfect ring. The number of uredosporic
patches varies with that of the spermogonial ones, but may be very considerable,
fifty or sixty being frequently present on the under-surface of a single leaf. Up
to a certain time the spermogonio-uredal areas appear as conspicuous green
patches when the leaf on which they are situated fades prematurely. When this
does not occur, however, they ultimately dry up and become brown and brittle,
readily breaking up and leaving no traces behind, save perforations in the lamina.
Before passing on to details regarding the mycelium and spores of this