THE COTTAGE GARDENER AND COUNTRY GENTLEMAN’S COMPANION, September 1 , 1857. 847 
blood red, or almost to black, have a pleasing effect on the 
white ground, formed by the filaments radiating from each 
of the globose sessile fructifications. Every one of these 
fructifications when detached carries with it, like a Medusa’s 
head, its radiating serpentine hair, and as the greater part 
of these filaments separate from the entangled ground 
without laceration, that is, with their extremities closed and 
convex, I conclude that these filaments have no connection 
for the purpose of suction with the interior of the plant on 
which the Erysiphe fixes itself. I am rather disposed to 
consider them as aerial roots, or rather as fronds analogous 
to those of Lichens, an analogy which appears to me to 
extend to other parts of the fructification. The oval spores 
of the Erysiphe communis , from four to eight in number, 
are contained in extremely transparent utricles, formed of a 
coarse membrane of 0045 millimetres in length, implanted 
on the conceptacles by a connecting surface of 0 - ll milli¬ 
metres in diameter, not unlike the asci of Lichens. It is 
not my intention to enter into any more circumstantial 
description of the Erysiphe, or of its mode of propagation. I 
have only incidentally mentioned its structure, in order to 
show more clearly how very different it is from the cryptogam 
of the Grape. 
Having cleared up this point there yet remains the most 
important question. Is the cryptogam the cause or the 
consequence of the disease of the Grape ? I have not the 
presumption to solve this difficult problem; it would be 
necessary to have data more evident, more incontestable, 
and more detailed, to establish any unde¬ 
niable demonstration. I will only state 
that I am for various reasons disposed to 
adopt rather the opinion that the appear¬ 
ance of the mildew is owing to a morbid 
change which the Grape has previously 
suffered. 
Last year I collected bunches of Grapes, 
branches of Vine, leaves of Gourds, Roses, 
and Chrysantliema, all covered with their 
respective mildews, and shut them all up 
in a wooden box, with the intention of scat¬ 
tering in the following spring, over healthy 
individuals of different kinds, the repro¬ 
ductive sporules which it was to be pre¬ 
sumed existed amidst the mycelia, and 
thus, as it were, to inoculate the disease. 
The experiment was carried out in June 
this year without producing any cryptogam. 
It might be supposed that the spores had 
lost their vegetative powers by too length¬ 
ened a state of desiccation. I therefore 
repeated the experiment in the month of 
July, making use of fresh mildews which 
had appeared naturally; the result was 
the same, the healthy Grapes were not 
attacked. From this it would follow that 
the mildew does not produce the disease, 
or at least that one condition was wanting 
—the predisposition to contract a disease. 
I feel, indeed, the force of the objections 
that may be made to my experiments as 
being made upon too limited a scale ; but, 
however small, still some value must be 
attached to them. 
The Secretary of Correspondence of our 
Academy has suggested to me that I 
should try the inoculating Grapes already 
diseased, first removing carefully the mil¬ 
dew which may be upon them. I purpose 
to take it in hand during my next stay in 
the country ; in the mean time, what I am 
about to state may supply the place of the 
experiment, and I think speaks pretty 
clearly. In a vineyard outside the Porto 
S. Niccolo, near the walls, I was, a few 
days back, examining a Vine covered with 
Grapes in the worst state; the farmer 
observed to me that they had been medi¬ 
cated, and that for a time they had ap¬ 
peared to be cured. I took two Grapes 
and placed them under the microscope: 
I found on the Grapes many crystals of 
urine mixed with other matter, which 
showed that they had been drugged. But 
the cryptogam had reappeared as fresh as 
usual, and as thick as upon the non-medi- 
cated Grapes. I hear that a great number 
of similar facts might be quoted, and they 
appear to me to prove two things: first, 
the inefficacy of the remedies hitherto 
used, and secondly, that the evil origin¬ 
ates in the Grapes themselves, or, in 
other words, in a predisposition to contract 
disease. 
The authors who have treated of the 
Fig. 3 
Fig. 2. 
(l . 
w WPf 
Fig. i represents a small portion of the surface of a Grape on which the cryptogam 
h»« an read itself magnified to 300 diameters. From the mycelium arise momliform 
filaments m, and the sporangia s. Two of the latter have an utricle directly attached 
t0 S C Fig U . P 2 P the 6 spo^gium is represented magnified tofiOO diameters, and by its side 
are the spores it has emitted, which, taken separately, are as transparent as white 
class* seen in a mass they have a very slight yellow tint. In Fig. 3 are three 
spores magnified to 1800 diameters, in order to show the nuclei or globules at their 
extremities, nifie^ diameters, shows at x three utricles in germination. At y are 
two fresh utricles, showing the little globules and the mucilaginous liquid contained 
in them. At z is an utricle shrivelled up by lateral compression, which has given 
rise to the optical illusion of a longitudinal slit. 
