Notes on the Life-history of Ravenelia sessilis, B. and Ravenelia
stictica, B. and Br.

BY

D. D. CUNNINGHAM, M.B.,

BENGAL MEDICAL SERVICE.

    During the past few years I have, as opportunities presented themselves,
been accumulating notes on the life-history of the two species of Ravenelia
mentioned in the heading, and as these now are fairly complete save in regard
to one or two details, it appears to be worth while to publish them, more
especially in consideration of the very imperfect knowledge which has as yet
been arrived at in regard to the peculiarities of the genus. In so far as I am aware,
all that is yet known is that Ravenelia is a genus of the Uredineæ producing
uredospores and very peculiar teleutospores. In regard to the development of
the latter, however, there would appear to be no accurate information, and in re-
gard to the presence of any other forms of fructification no information of any
kind. In the present paper I hope to be able to show that in both species a
development, of what must apparently be regarded as spermogonia forms the
starting-point of each annual cycle of development, and that in Ravenelia sessilis
no less than five different forms of reproductive bodies are present,—spermatia,
two forms of uredospores, and two forms of teleutospores.

    Both species are extremely common in the neighbourhood of Calcutta,
R. sessilis occurring on a large number of trees of Albizzia Lebbek, and
R. stictica appearing everywhere on the leaves of Pongamia glabra.

    Taking R. sessilis first and the period of complete defoliation of the host,
which occurs in the beginning of the hot weather—as a rule during March—
as a starting-point, we find the following series of phenomena manifesting itself.
For the brief period during which leaves are entirely absent the only sites on the
trees of Albizzia Lebbek on which any traces of the parasite are to be found are
the dried-up and ripening pods, many of which remain adherent for a consider-
able period after the new crop of leaves has fully expanded. On these the
remains of large teleutosporic clusters, and sometimes of mixed ones containing