W. G. Farlow—Disease of Olive and Orange Trees. 41 
into four parts by cross partitions. They are not contained in 
asci, but are attached to short filaments which line the surface 
of the base and lower portion of the sides of the flask. They 
escape readily through the open mouth ; and slight pressure on 
the covering-glass generally causes a fresh discharge. 
So far, we have spoken of the fungus as seen on the olive. 
The orange-leaves sent us are also covered with a black sub- 
stance, which is not so much in spots as in powdery sheets upon 
both surfaces of the leaves, more particularly the upper. e 
attachment to the leaf is by no means as strong as in the olive; 
and the deposit can easily be scraped off, even without previous 
moistening. In fact, in some places it falls off on the slightest 
© specimens of diseased orange-stems were received 
for examination. A microscopic examination shows why the 
deposit was more easily removed from the orange than the olive 
eaves. The smooth surface of the former gives no permanent 
attachment to the fungus, which, as we have before said, does 
not penetrate into the interior of the cells of the mother plant; 
while, on the other hand, the hyphw wind themselves tightly 
around the stalks of the stellate hairs of the olive, from which 
they cannot be removed. If the fungus should attack both 
oranges and olives, it is very evident why the latter would suffer 
much more than the former. Apart from the absence of hairs, 
which invariably constitute a large proportion of the scrapings 
of the olive-leaves, that from the orange-leaves is precisely iden- 
tical—the same moniliform hypha, bearing Macrosporium and 
Helminthosporium spore-like bodies, the same pycnidia and sty- 
lospores. Micrometric measurements only confirm the identity. 
On the orange-leaves sent me, there is a greater proportion of 
pycnidia, and a smaller proportion of stylospores, than in case of 
the olive-leaves; but that is, of course, an accidental difference, 
as the olive-leaves themselves vary. On the orange, the propor- 
tion of Helminthosporium-like spores is much greater than on 
the olive; but, from the facility with which the so-called second- 
ary forms of fruit are produced in fungi, and their great varia- 
bility, that it is not a fact of any importance; and we can in the 
a decided manner affirm that the fungus is the same on both 
plant 
The first account of a fungus growing es orange-trees, re- 
: ; ws 
quz sspe tota induit.” ter, Turpin published an account, 
with a figure, of a species which he also called Fumago Citri, 
which ontagne made the type of a new genus, Capnodium, 
