arent to a casual observer. Mr. Mayne, like
many persons at the time, attributed the blight to an insect which some
called _Aphis Vastator_, others _Thrips minutissima_. There was a glass
case in the Dublin Exhibition of 1853, showing this insect feeding on
the leaves and stalks of the potato plant. Mr. Mayne and those who
agreed with him, seem, in this instance, to have mistaken cause for
effect. Indeed the insect, it would appear, was a natural parasite of
the potato, and some observers have gone so far as to assert that the
_Aphis Vastator_ abounded more on healthy plants than upon those
affected with the blight.

[113] _Letter to the Duke of Leinster quoted in Irish Census for 1851_.
M. Zander, of Boitzenberg, in Prussia, published, about this time, a
method by which full sized potatoes could be produced in one year from
the seed, and he further stated that the seedlings so produced had
resisted the blight. The old idea was, that it took three years to
produce full-sized potatoes from the seed. M. Zander's method was tried
in various parts of Ireland and England, its chief peculiarity being
that the seed was sown on a light hot bed, and the plants so produced
were transferred to the ground in which they were to produce the crop.
Full-sized potatoes were the result, each plant producing, on an
average, 1-1/2 lbs. of potatoes, or rather more than 29 tons to the
Irish acre. This method appeared satisfactory to those who interested
themselves about it, but it does not seem to have been followed up.

[114] Proceedings of the Royal Dublin Society.

This opinion as to fogs preceding or accompanying the potato blight was
corroborated from various parts of the United Kingdom. A correspondent
of the _Gardener's Chronicle_, under date 14th Nov., 1846, writes: "In
the early part of August, 1846, there was not a diseased potato in the
North Riding of Yorkshire. Late in August, I think the 25th, a very
thick dense fog prevailed. The air was not, however, at all _chill_. The
heat and closeness was most oppressive. This continued all night, and
anything similar to it I never before saw, with so high a temperature.
It occurred also on the following night. _On the morning after the fog,
the whole of the potato fields had precisely the disorganized appearance
they have after a night's frost_. They soon became black, and the
disease followed in a very few days."

In the _Gardener's Chronicle_ of the 5th of September, it is mentioned