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POPULAR SCIENCE REVIEW. 
plants of all kinds are more or less subject to their ravages. 
Some are more susceptible than others, of which the corn and 
grass tribe, or Graminacece , as they are termed by botanists, is 
an example. Not less than thirty species have been recorded 
upon plants of this natural order, and of these nearly one-half 
are found upon the living plants. Upon the potato plant, 
again, no less than ten different kinds of Fungi have been 
described ; whilst upon other and more fortunate plants only 
one or two parasites of this nature establish themselves. 
Potato Mould. — Towards the close of the summer of 1845, 
in the course of a few weeks, every one became aware of the 
fact that a new disease had appeared which threatened the 
entire destruction of. the potato crop. Until then it seemed 
to have been almost, although not entirely unknown. It first 
appeared in the Isle of Wight about the middle of August, 
and a week afterwards had become general in the South of 
England, and the next week there were but few sound samples 
of potatos in the London market. Early in September the 
disease had commenced its ravages in Ireland, and shortly 
afterwards it was discovered in Scotland. With the same 
rapidity it seems to have spread throughout Europe and 
North America, or at least the western portion of the former 
and the northern districts of the latter. It must not be 
imagined, however, that the Isle of Wight was the centre 
from which this disease spread over such an extended area 
and with such alarming rapidity. From this spot it doubtless 
made its first appearance that year amongst our own crops, 
but there is not the least doubt of its existence both on the 
continent of Europe and in North America in the previous 
year, and the farmers of Belgium had noted its appearance in 
the province of Liege as far back as 1842 and 1843. Other 
diseases had been observed affecting the potato crop before, 
and one which was also associated with a parasitic fungus had 
made its appearance in 1815. It is also exceedingly probable 
that, in a milder form, the murrain was present with us a 
year or two before it broke out to such an alarming extent. A 
correspondent to the Gardener’s Chronicle, in 1844, notices it 
in the Isle of Thanet, and another testifies to its occurrence 
in districts of Ireland for two or three years previous to its 
general outbreak. The description of the disease in Canada, 
in 1844, contained in a letter addressed to Dr. Bellingham, 
and quoted by the Bev. M. J. Berkeley,* leaves no doubt of 
its identity : — 
During the months of July and August (1844), we had repeated and heavy 
showers, with oppressive heat, and an atmosphere strongly charged with 
* Journal of Horticultural Society of London, vol. i. p. 11. 
