Medical Officers of the Army of India.
31
dation to the parasite. In bodies of water containing Nymphœa rubra there is
certainly never such an entire disappearance of the host-plants, but there is at
the same time a seasonal disappearance of the parasite. Where however,
as in the case of the other two Nymphœas, there is prolonged continuous
absence of the host-plants, the parasite would necessarily die out if only capable
of parasitic existence, for the spores have not the character of resting cells, but
germinate at once on attaining maturity. The continuous development of
conidia by yeast-like multiplication originating with the sporidia tides over the
period of absence of host-plants and provides for the infection of the latter
when they again make their appearance.
The parasite when occurring in Nymphœa lotus and Nymphœa rubra presents
the same general features as in Nymphœa stellata. The spores are not, how-
ever, so exclusively limited in their distribution to the substomatic spaces, but
not unfrequently occur also in the large cavities immediately above the inferior
epidermis. In Nymphœa lotus the areas affected by the fungus appear as
yellow spots and patches like those in Nymphœa stellata, whilst in Nymphœa
rubra they appear as pinkish spots in the dark-red surface of the leaves. Where
such spots are very abundant the presence of the parasite often appears to
exert a very special action on the tissues of the host, the chlorophyll in the
cells of the affected areas persisting after decay has set in around. This phe-
nomenon is not peculiar to this parasite, but often appears very much more
conspicuously in others; for example, when the leaves of Albizzia Lebbek
affected by Ravenelia undergo the ordinary seasonal change of colour preparatory
to falling off, the patches of Ravenelia appear as conspicuous brilliant green
spots on the general bright yellow surface and remain as such long after the
actual fall of the leaf due to persistence in the chlorophyll content of the host-
cells of the affected areas. The phenomenon almost would appear to indicate
the presence of a lichenoid symbiotic relation between the fungal and host
tissues in place of a merely parasitic one.
When we come to consider the nature of the parasite, we can have no
hesitation in referring it to the Ustilagineœ, but the question of its precise
place in the family and of its claim to be regarded as belonging to a distinct and
new genus still remains to be discussed. The peculiar characters of the pro-
mycelium and the terminal development of the sporidia at once indicate a close
relationship to both Tilletia and Entyloma, and, as the ripe spore mass is
neither pulverulent nor dusty, specially to the latter genus. There are, however,
certain distinctive features present which are, I believe, of generic value. These
are, first, the subterminal development of the spores; and, second, the develop-
ment of the sporidia, not directly on the tip of the germinal tube, but on a series
of intermediate structures which occupy the place of the sporidia in Tilletia and
Entyloma. The fact that conjugation never occurs in the bodies at the tip of
the germinal tube is sufficient to show that they are not to be regarded as