Botanical Society of Edinburgh. 279 
state, as if they had been filled with fluid by endosmose, and the com- 
partments of the cellular tissue had thus become so entirely detached 
from each other, as to have assumed a complete round form, instead 
of their characteristic hexagonal shape. It appeared to him to re- 
semble what might be expected from the maceration of the textures 
in water, and it was a possible supposition that this might be the 
first stage of the disease, and that the change thus effected in the 
tuber formed a nidus fitted for the development and growth of the 
fungus already existing in the aérial parts of the plant. . 
Mr. Milne being invited by the President to give his opinion, stated 
the gratification with which he had listened to the statements made 
by Mr. Goodsir and other speakers. Nothing could be more distinct 
than the description given of the nature of the fungus which ap- 
peared 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 speculations on its probable effect 
in altering the condition of the potato. No one had as yet offered 
any opinion as to the circumstances 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 atmosphere, was there anything in the state of the at- 
mosphere 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 that he had made a discovery, which would 
explain the appearance of the disease in some places and not in 
others. But he had not come prepared to enter into particulars, not 
supposing that any persons, unless they were members of this So- 
ciety, could take part in the proceedings ; he would therefore indi- 
cate generally the results. Mr. Milne then described some peculia- 
rities of the weather in England and Scotland 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 Scotland, where the potato disease had not appeared, 
the maximum heat had occurred in August as usual. He alluded 
also to repeated and sudden thermometric changes which had occurred 
in the south of England. 
Mr. Brand and Mr. Girdwood remarked, that potatoes in the early 
part of the season were not affected, and that where the stems and 
leaves had been cut away early, the disease had not appeared in the 
tubers left inthe ground. These facts seem to indicate some atmo- 
spheric influences which had come into operation late in the season, 
or some cause which did not take effect- till the tubers were fully 
developed. 
2. “‘A Synopsis of the British Species of the genus Rubus,’ by 
Charles C. Babington, M.A., F.L.S. &c. (This paper isin the course 
of publication in these Annals. ) | 
