106 
THE POTATO DISEASE. 
Artotrogus hydnosporus, or at least a mucorine fungus according 
with the description of Montagne, excepting that in my speci¬ 
mens the spores appear tuberculated or granulated, and not bristly; 
but this may possibly depend on age. It inhabits the cavities of 
the cells, perfecting its spores within them, and I think its creep¬ 
ing filaments perforate the cell-walls. It is proper to mention 
that the same microscopic power has been used in all these ob¬ 
servations. In last August these potatoes, then clearly diseased, 
contained no fungus ; now, being further advanced in decay, they 
contain it in tolerable abundance. I believe I am therefore 
justified in expressing my confirmed opinion that the potato 
murrain, at least as far as the destruction of the tubers is con¬ 
cerned, is not produced through the agency of the cryptogamic 
parasites.” 
All this seems to infer that it is to atmospheric influences the 
origin of the disease should be ascribed, the presence of fungi 
being no more than the outward symptoms. Last summer and 
autumn the weather was particularly favorable to the develop¬ 
ment of these bodies; mushrooms were remarkably abundant, 
puff balls and the large Bovista gigantea were springing up on 
all sides, old trees wore a complete mantle of the Polypori, and 
smaller species were discoverable wherever a piece of ground or 
refuse matter was allowed to remain, even for a short time—all 
indicating the almost universal presence of the germs of fungoid 
bodies, and the peculiar fitness of the atmosphere for their growth 
wherever they could effect a lodgment; and by accounts received 
from various countries this state of aerial influence seems to have 
been common in all, or nearly all, the temperate regions of the 
earth. It is not wonderful, then, when we consider that the 
majority of fungi require the presence of some decomposing sub¬ 
stance for their development, and that, like certain classes of 
insects, they are only seen on the particular substance suited to 
each; that in a season like the past this potato fungus should 
have been found on the stems and in the tubers after that they, 
through the influence of that ungenial weather, had become un¬ 
healthy. The plain deductions from these inferences are, that the 
excessive moisture and consequent absence of solar heat, had 
caused a superabundant accumulation of crude aqueous matter in 
the organism of the potato which was carried to an extent sufficient 
