was most virulent on wheat
lands which had been manured with guano.

In the first week of September, the potatoes in the London market were,
to a very considerable extent, found to be unfit for human food. To the
eye they did not show any sign of disease, but when boiled and cut its
presence was but too evident, by the black, or rather brownish-black
mass they presented. The potato fields began to be examined, and the
provincial journals soon teemed with accounts of the destructive
visitation, with speculations concerning its cause, and suggestions as
to probable remedies. The descriptions of the disease given by the
English newspapers do not quite agree with the symptoms observed
somewhat later in Ireland. "Whatever may have been the cause," says one
account, "it is certain that, externally, the disease indicates itself
by a fungus or moss producing decomposition of the farinaceous
interior."[57] "The disease is very general in this locality," says
another, "beginning with a damp spot on some part of the potato."[58] A
third observer writes: "The commencement of the attack is generally
dated here from Tuesday, the 19th ultimo. A day of the heaviest rain
almost ever known. It first appears a bluish speck on the potato, and
then spreads rapidly."[59]

Whether it was that, in England, in their anxiety about the tuber,
people paid little or no attention to the stems or leaves of the potato;
or, that the earlier symptoms differed from the later, matters but
little, the disease was certainly the same throughout the United
Kingdom. In Ireland it was first observed on the leaves of the plant as
brown spots of various shapes and sizes, pretty much as if a dilution of
acid had fallen upon them like drops of rain. Sometimes the blight made
its appearance near high hedges, or under trees; sometimes portions of a
field would be greatly affected with it before other parts were touched
at all; and I have sometimes observed the very first symptoms of the
disease opposite an open gateway, as if a blighting wind had rushed in,
making for some distance a sort of avenue of discoloured leaves and
stalks, about the width of the gateway at first, but becoming wider
onwards. When the decomposition produced by the blight was in a somewhat
advanced stage, the odour from the potato field, which was very
offensive, was perceptible at a considerable distance. There may have
been cases in this country in which the disease was first observed in
t