THE POTATO DISEASE. 
105 
of the fungus which appeared to accompany the disease, and the 
parts of the potato affected by it. The discussion, however, had 
been confined entirely to a description of the fungus, and to spe¬ 
culations on its probable effect in altering the condition of the 
potato. No one had as yet offered any opinion as to the circum¬ 
stances which led to the production of the fungus. If it arose 
from seeds dormant in the potato, what was it which had caused 
them to germinate ? If it arose from seed or matter in the at¬ 
mosphere, was there anything in the state of the atmosphere to 
account for it in one part of the globe and not in another ? He 
had been devoting attention to the meteorological branch of the 
inquiry, and he thought he had made a discovery which would 
explain the appearance of the disease in some places and not in 
others, but he was not then prepared to enter into the particulars 
he would, therefore, indicate generally the results. Mr. Milne then 
described some peculiarities of the weather in England and Scot¬ 
land during the summer and autumn of last year, as shown by 
meteorological returns which he had obtained from a number of 
places, both in those districts where the disease prevailed and in 
those from which it had been absent. He mentioned that the 
maximum summer heat had occurred in England and the southern 
parts of Scotland in June; whereas in the northern parts of Scot¬ 
land, where the potato disease had not appeared, the maximum 
heat had occurred in August, as usual. He alluded also to sudden 
thermometric changes which had occurred in the south of Eng¬ 
land, as probable agencies in the development of fungoid boohes.” 
In a paper by H. 0. Stephens, Esq., which we extract from 
the ‘ Phytologist, 5 is the following very important opinion, 
borne out to a great degree by subsequent considerations: “ In 
a former paper I expressed an opinion that the fungi found in 
the diseased tubers were to be considered rather as an accidental 
accompaniment than the proximate cause of the disease, and that 
I considered it improbable that the Artotrogus could be the cause 
of their decomposition, because that fungus was not invariably 
present; and that up to the period at which that communication 
was written I had not succeeded in detecting it. Subsequent 
observations have convinced me that this inference was correct. 
The identical sample of potatoes which were then free from cryp- 
togamic organisms now certainly contain them. I now find the 
