408 BULLETIN OF THE BUSSEY INSTITUTION. 
flasks is quite variable. The central portion of Fig. 1 represents one of 
the more regular, where, starting from a somewhat contracted base, there 
is a regular swelling of the central portion, which again diminishes into 
a rather long neck of uniform size. In some cases, the flask, instead of 
being straight, is flexuous with two swellings, the upper one being 
smaller than the lower. Others, still, fork, and usually one branch is 
much more obtuse than the other. The size of the flasks varies very 
much; but, even in their younger states, they can generally be distin- 
guished from the pycnidia by being less inclined to a spherical shape. 
The height is as variable as the outline. Some of the smaller are .15 
mm. high; others—and they are nearer the average — are .4 mm. 
The wall of the flasks is composed of dark-colored cells, which are 
longer in the direction of the axis of the flasks. 
In some cases, the cells, composing the wall of the stylospores, grow 
outwards, so as to form papillae; and, as the mycelium at the base 
generally sends up branches around the flask, it is only by a careful 
dissection that the base can be clearly seen. At first, the mouth is 
closed, and there is a depression of the cells at the centre; but, later, 
they spring back so as to form, round the open mouth, a circle of 
slightly reflexed teeth, whose tips are perfectly hyaline. The neck of 
the flask is hollow; but, in the swollen portion, spores are borne. 
They are oval, and divided 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 substance, which 
is not so much in spots as in powdery sheets upon both surfaces of the 
leaves, more particularly the upper. The 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 touch. No 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 leaves. The smooth surface of the former gives no perma- 
nent 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 
