On the Potato Disease. 
361 
As regards the weather of the jear 1845, this had been very 
favourable for planting and hoeing, and the appearance of the 
growing crops was for the most part as promising as could be* 
wished up to the beginning of Juij', when they were rather at a 
stand for want of some showers, the weather having been very 
drj' and hot, with only one or two slight exceptions, for six weeks, 
the thermometer ranging in fact, according to the registry kept 
at the Horticultural Society's Garden, from 1^° to 4^° above the 
average for the last nineteen years ; in short, it was beautiful hay- 
making v.'eather. It then suddenly changed to the most extra- 
ordinary contrast that ever 1 witnessed even in this fickle climate ; 
the atmosphere being for upwards of three weeks one continued 
gloom, the sun being scarcely ever visible during that time, with 
a succession of the most chilling rains and some frost ; and for 
six fallowing weeks the thermometer ranged but from 1^' to 7^ 
below the average for tVie last nineteen years. Still the crops, upon 
a general view, did not look worse than they usually do alter being 
beaten about t)y heavy rains ; that is to say, they had a soddened 
appearance. That they had become debilitated I cannot entertain 
a doubt, but they exhibited at that time no other signs of it than 
that. But again the weather became suddenly dry and hot, and 
continued so up to (he latter part of September, at which time the 
light Imds were as dry as dust as deep as the plough had pene- 
trated. I of course only speak of those places which I visited; 
but I may perhaps be allowed to state, upon the authority of the 
gentleman before mentioned, who is also the occupier of one or 
two farms, that a similar extreme variation of the weather oc- 
curred in Nova Scotia, namely, " very unusual cold 7'ains, suddenly 
succeeded by 90' of heat." It also appears from accounts from 
Prance, Belgium, and other countries visited by the disease, that 
their season was very similar. M. J. Decaisne, in his excellent 
" History of the Potato Disease," p. 75, says, " The unusual heat 
at the beginning of July was suddenly succeeded by a long con- 
tinuation of extraordinarily cold, humid, and cloudy iceather." 
Various other causes have been assigned for the disease ; the Rev. 
M. J. Berkeley, in an elaborate memoir illustrated by several 
varieties of parasitic fungi, attributed it to the insidious attack of 
a species of botrytis, which, singularly enough, had never been 
observed before, and was named in consequence by Mile. Libert* 
(who is said to have first discovered it) " devastatrlx," by M. 
Montagne "infestans," and by M. Desmazieres, "fallax." 
When it was first noticed, it was said to thrive only on the 
living leaves of the potato, sparing even the stalks; it has, 
however, been admitted since, that it attacks the stalks and 
* The Rev. M. J, Berkeley. 
