Medical Officers of the Army of India.
119
plant, as they are almost invariably entirely destroyed at one or other stage of
their development. So much so is this the case, that, as a rule, no garden varieties
of Papaver somniferum are cultivated in the Botanical Garden at Shibpur, and on
the exceptional occasions on which an attempt is made to grow them, even from
seed imported direct from Europe and after the cultivation has been intermitted
for periods of several successive years, the disease invariably makes its appear-
ance to foil it. A very striking instance of this fact presented itself during the
course of the present year. No varieties of opium-poppies had been grown in the
garden for eight or ten years previously, but in the winter of 1894 a large bed
was planted with seedlings which had been raised from seed freshly imported
from Europe in the autumn. As usual they grew vigorously and they had
even come into full flower in apparently perfect health, but whenever the tem-
perature began to rise steadily towards the end of February, the blight
suddenly made its appearance and spread with such rapidity that within the
course of a few days every plant was attacked and killed by it. The relatively
high nocturnal temperature and the drenching dews of the deltaic area are
specially favourable to the rapid extension of the disease, because they provide
conditions favouring the development and evolution of the aërial fructification of
the parasite which is the essential cause of it, but, although its destructive effects
are not invariably so excessive in dryer regions, it is by no means absent from
them and is occasionally a cause of serious mischief there. The very first
specimens of the blight which I had an opportunity of examining were sent down
from Behar in the year 1874, when it was the cause of very serious damage to the
local cultivation of the opium-poppy there.
The presence of the disease is from the outset very readily recognisable
from the conspicuous effects which it produces on the affected leaves. They
show patches of pale-brown discoloration, which are generally primarily situated
towards the tips and margins of the laminæ, but rapidly spread, become con-
fluent, and involve the entire foliar surfaces, which at the same time wilt and soon
become dry and brittle. The blight as occurring in Europe is described as occa-
sionally affecting the stems of the plants more conspicuously than the leaves ;
but in India this phenomenon, if it occur at all, must be very rare, as I have
never encountered an instance of it. If the under surfaces of the affected leaves
are examined with a lens in the earlier stages of the disease, especially in the
early morning and before the dew has evaporated, they are found to be covered
by a whitish or very pale ochreous coating of minute, erect, branched filaments
bearing terminal sporangia, and, under somewhat higher magnifying powers, it
will be seen that they emerge from the interior of the lamina by the stomatic
orifices. In the earlier stages of the disease these are the only fungal elements
recognisable on the foliar surfaces, but, subsequently, the dead tissues become
invaded by saprophytic fungi of many different kinds, the conidial and peritherial