266 
THE COTTAGE GARDENER AND COUNTRY GENTLEMAN’S COMPANION, July 28, 185: 
are visible on the organs affected by the fungus even with the 
naked eye, but more certainly with a lens. Such specks 
must be chosen for examination, for those parts which are 
in a more advanced stage of decay, in which the specks 
have become enlarged, are useless for this purpose; in 
consequence of which, in my earlier investigations, in which 
I had before me the later stages of disease, the relations in 
question were not satisfactorily explained. Thus much is 
now clearly established: amongst the youngest threads of 
Mycelium, where they radiate on all sides from the margin 
of the spots, the cuticle retains its normal green ; amongst 
the older parts of the threads, on the contrary, little brown 
specks (Figs. 1 & 3, a a) are visible. That this appearance 
is not accidental (for indeed the dead and fallen hairs, for 
example, on the under side of the nerves, leave little specks) 
is at once clear when a part of the cuticle is placed under 
the microscope, already covered with the network of the 
threads of the Mycelium, for in this case the dots occur 
with the greatest regularity only beneath the threads of the 
fungus, and therefore arranged after the fashion of a net. 
A good lens will exhibit this phenomenon, but perfect con¬ 
viction can be obtained only by means of the compound 
microscope, employing for the purpose an objective fitted 
Various states of the Vine Mildew. 
with Lieberkiihn’s mirror and adapted for opaque objects, 
since we can then see the most delicate threads and the 
connection of one spot with another. 
If we examine the specks more accurately, which is best 
done with transmitted light in extremely thin horizontal 
slices of the cuticle, we perceive that the threads of the 
fungus have on their under side, exactly corresponding with 
each brown speck, an irregular lobed process, by which it is 
firmly attached to the epidermis (Figs. 2 & 4, b b). Those 
processes which are nearest the tips of the threads of the 
Mycelium are frequently as colourless as the threads them¬ 
selves, but most of them have assumed a brown tint, with 
which a diseased state of the epidermal cells with which 
they are in contact is constantly combined. The contents 
of these cells become brown and contract irregularly, while 
the walls themselves acquire a similar tint, which is deeper 
in those which are lateral. This degeneration of the tissue, 
which at first is confined to the cells in immediate contact 
with the processes, seizes at a later period also the neigh¬ 
bouring cells to a greater or less extent. In this manner 
there arise upon the berries little knots which are perfectly 
visible to the naked eye, and on the branches the large 
brown spots described above. 
There can be no doubt that we have in 
these processes the points from whence the 
parasitic fungus exercises its baneful in¬ 
fluence on the Vine, as it is in contact with 
them that the cuticle becomes diseased, in¬ 
ducing the destruction of the outer layers 
of bark, and in the berries preventing the 
further growth of the skin, and, in conse¬ 
quence of the continued undisturbed growth 
of the pulp, the rupture of the fruit. At the 
same time the most certain proof that the 
disease of the Vines does really proceed from 
the fungus is afforded by these relations, and 
more especially in the above-described series 
of phenomena. 
I have already stated above that the leaves 
are not eligible for this purpose. The pro¬ 
cesses and brown spots are not produced on 
the firm cuticle of the upper surface of the 
leaves, nor have I found them in the in¬ 
terstices of the veins of the under side, but 
only upon the cuticle of the veins them¬ 
selves, where, however, their examination is 
very difficult, in consequence of the thickset 
hairs with which the veins are clothed. Con¬ 
nected possibly with this protection against 
the attacks of the fungus, which the paren- 
chym of the leaves enjoys, is the fact that the 
growth of the leaves, even when thickly 
coated with fungus, is not impaired; the 
parenchym of the leaf does not become brown 
like the outer strata of bark, and the nourish¬ 
ment of the plant, at least according to the 
investigations recorded above, seems to remain 
normal. 
The first discoverer of these processes was 
Dr. Zanardini, at Venice, who, on the 19th of 
July, 1851, made a communication respecting 
them to the Venetian Institute, and gave them 
the name of fulcra. I cannot, however, agree 
in many respects with the description which 
is given of them with reference to the ob¬ 
servations of Prof. Visiani in the above- 
mentioned report of the Venetian commission. 
Visiani believes that he has discovered that 
they penetrate into the epidermal tissue after 
the fashion of roots. This I have never been 
able to establish, but I find, on the contrary, 
the cuticle perfectly entire (as Amici asserts, 
who, however, appears not to have recognised 
these organs), and the processes themselves 
attached only superficially, and in many cases 
even separable, together with the threads of 
the Mycelium (Fig. 4,6 6) without injury. 
In a second point again I cannot confirm 
the observations of Visiani. He asserts that, 
at the place where the processes spring from 
