FUNGI. 405 
which have a swollen or moniliform appearance, 
probably owing to repeated abortive attempts to 
produce fruit, and others develop a number of 
ovoid and transparent spores, and among them 
bodies of a larger size which mature within them- 
selves zoospores by a differentiation of their con- 
tents, is invariably connected with the disease, 
and is found on the decaying plants ; the growth 
of the fungus being aided by some predisposition 
es 
3 & 
Fic. 49.—PERONOSPORA INFESTANS. 
(z) Young plants. (2) Full grown. (3) Spore.—All magnified. 
in the state of the vegetable, induced by the soil 
or the atmosphere. The potato is commonly 
affected after the tubers have been formed, and 
have attained a considerable size. It first attacks 
the leaves entering by the stomata or breathing- 
poreson the under side, and covering them with 
brown blotches, as if they had been burnt by the 
“action of sulphuric acid. From the leaves it 
