ON FUNGOID DISEASES OF THE VINE. 
75 
to twenty minutes, the motion becoming.gradually slower ; at the 
end of that time it ceased, the cilia dropped off, the zoospores 
assumed a spherical shape, and in a quarter of an hour an out¬ 
growth appears at the side, which developes rapidly into the 
mycelium of a new plant. Dr. Earlow states that he never saw the 
direct production of hyphse from the conidium itself, hut always 
from the zoospores. 
As to the rapidity and regularity of this germination, he observes 
that it was so regular that by properly arranging the time of sowing 
he was able to be tolerably certain of a crop of zoospores for class 
demonstration at any given hour. In about two hours from the time 
of sowing the conidia the intermediate stages will have been passed, 
and germination of the zoospores commenced. Time and time again 
he has sat with his watch before him observing the changes, and 
almost punctually to the minute the dischargejof zoospores hasbegun. 
Oogonia have only been found by him on Vitis cestivalis , in 
the latter part of September and October, in the shrivelled parts of 
the leaves, and most abundantly just inside what are called the 
palisade cells of the upper surface. They are spherical, '03 m. in 
diameter, smooth, with a thick yellowish epispore, but hitherto he 
has been unable to secure their germination. Perhaps he may not 
have given them a sufficient period of rest. 
In order to complete his investigations in all possible practical 
directions, we find that Dr. Earlow pursued some successful ex¬ 
periments in inoculation. This was done by placing healthy 
leaves upon infected leaves and covering with a moistened bell- 
glass. In two cases the Eungus appeared on the healthy leaf at 
the end of the second day. Again, germinating zoospores were 
sown on healthy leaves of Vitis vinifera and of smooth-leaved 
American species. The Eungus appeared on the leaves of Vitis 
vinifera on the fifth day after sowing ; on American species a day 
or two later. The Eungus grew luxuriantly on Vitis vinifera , and 
soon covered the leaves. There is no reason to doubt, if once intro¬ 
duced into England, it would soon establish itself. 
This parasite is very abundant on leaves of Vitis cestivalis , 
Vitis Zabrusca, and all their cultivated varieties ; on Vitis cordi- 
folia , Vitis vulpina, and the cultivated Catawba Grape ; and in fact 
on nearly all varieties of American Grapes, although it has not 
been recorded on the Diana Grape. It is probably found through¬ 
out the whole United States east of the Rocky Mountains, but it 
has not yet been reported from the west coast. 
