MOULDS. 
195 
electricity. Towards the close of the month of August I observed the leaves 
to be marked with black spots, as if ink had been sprinkled over them. 
They began to wither, emitting a peculiar, offensive odour ; and before a 
fortnight the field, which had been singularly luxuriant, and almost rank, 
became arid and dried up, as if by a severe frost. I had the potatoes dug 
out during the month of September, when about two-thirds were either posi- 
tively rotten, partially decayed and swarming with worms, or spotted with 
brownish-coloured patches, resembling flesh that had been frost bitten. These 
parts were soft to the touch, and upon the decayed potatoes I observed a 
whitish substance like mould. 
Although this disease made its first appearance, in the 
middle of August, 1845, in the Isle of Wight, it had already- 
appeared in Belgium in the same year, a month previously j 
and although it may have been noticed in other British locali- 
ties in 1844, it was known in Canada and in St. Helena in 
the same year to a far greater extent, and in Liege as early 
as 1842. There are, therefore, good grounds for believing 
that the European centre was Belgium ; but if M. Boussin- 
gault was correct in stating that “ this malady is well known 
in rainy years at Bogota, where the Indians live almost 
entirely on potatoes,” then it is not of European but American 
origin, and is probably derived from districts not far remote 
from those whence Europe first received the potato itself. 
It would occupy too much space to detail the different 
theories and opinions relative to the causes of this disease to 
which 1845 and subsequent years gave birth. Suffice it to 
say, that the lapse of years has silently proved the majority of 
these to have been fallacious. All such as imputed to peculiar 
electric conditions, a wet season, or other meteorological in- 
fluences, the disease which has re-appeared under different 
conditions and influences, and in seasons remarkable for dry- 
ness, are manifestly refuted ; whilst its mycological origin has 
continued to gain adherents, and the gradual accumulation of 
fresh facts has almost placed it beyond dispute not only that 
the potato disease is accompanied by, but results from, fungal 
growths. Unfortunately, this disease has been so prevalent, 
more or less during the past eighteen years, that few have been 
without the opportunity of making themselves acquainted with 
its external appearance. To this may be added the minute 
and exact account of its development, as recorded by that ex- 
cellent mycologist and careful observer the Rev.AL J. Berkeley, 
in 1846, and to which, even now, nothing of importance can 
be supplemented or abstracted : — 
The leaves began suddenly to assume a paler, and at length a yellowish 
tint, exhibiting here and there discoloured spots. More or less coinciding 
with these spots, on the reverse of the leaves, appeared white mealy patches* 
