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Scientific Memoirs by

and representing the rudiments of the flowers; and hence, just in proportion to the
rapidity with which the growth of the host primarily occurs, there will be a
diminished likelihood of the blight successfully establishing itself. The fact
that rice is so much primarily cultivated in seed-beds in place of being sown
broadcast in the fields, is thus probably one reason for the very limited extension
of the disease, as under such a system of cultivation the conditions providing for
very rapid initial growth are, as a rule, generally present.

      NOTE.—Since the above was written, Professor Oscar Brefeld of Munster has published a paper in the
Botanisches Centralblatt, *showing that this disease is not caused by a member of the Ustilagineae, but by
an Ascomycete, closely related to Claviceps purpurea, which gives rise to ergot in Rye and other Gramineae.
As, however, this discovery does not practically affect the measures for prevention which have been
recommended, and as true Ustilagineous disease frequently prevails amongst the grain crops in this country
to a serious extent the text has been allowed to stand as it originally was.

II.—Blights affecting Potato-crops in India.

     a. The common Potato disease of Europe. —This blight, which, as every-
one is aware, is dependent on the action of Phytophthora infestans, de By.,
one of the peronosporic group of oomycete fungi, has, of recent years, not
unfrequently appeared in epidemic and destructive form, and, in certain parts of
the country, such as the Khasi hills, in which the cultivation of the potato has
come to a great extent to replace that of indigenous crops, has occasionally
seriously affected the food-supply of the population. The introduction of the
parasite into the country would certainly appear to have taken place only
comparatively recently, and was no doubt effected by means of well-meant but
injudicious importation of large quantities of seed-potatoes from Europe, without
sufficient precaution that they were not derived from infected stock.

      The distinctive characters and the life-history of the parasite, so far as
this has as yet been ascertained, are so well known that it is unnecessary to
enter into any details regarding them here. Specimens of the disease have
reached me from the Khasi hills, from the Darjiling district, and from Kumaon,
but none as yet have been obtained from any portion of the plains of India. So
far, then, the disease would appear to prevail epidemically only in hill-areas.
This fact is no doubt to be accounted for by the differences in the external con-
ditions to which the crops are exposed within the two areas. When cultivated
in the hills they are constantly liable to be exposed to those conditions of atmos-
pheric humidity which permit of the development of the aerial fructification
of the parasite. (Plate. I, Fig. 12), of the continued vitality of the sporangia, and
of the general diffusion of the zoospores; whilst in the plains, as cold-season

   *Der Reis-Brand and der Setaria-Brand, die entwicklungsglieder neuer Mutterkornpilze. Von Oscar
Brefeld. Botanisches Centralblatt., Band LX V, 1896.