Hogg, on Vegetable Parasites. 
19 
fectly sweetj while No. 2 was more sour, and of a dark red 
colour ; the filamentous masses were broken up, and had fallen 
to the bottom of the fluid, and the surface was slightly covered 
with a mould. No. 3, although smelling somewhat like bad 
wine, was not much altered in colour, but on its surface the 
aspergillus was growing. Six months later No. 1 was per- 
fectly sweet, exhibiting well-marked spores and torulse ; 
No. 2 was rather more decomposed than it was on the former 
examination; and No. 3 remained the same. 
Now, upon comparing the fermentation of the achorion 
fungus with that of good healthy yeast, it will be seen to be 
almost identical. In the first place, it is as actively carried 
on by the former as by the latter. There is, however, just a 
slight diff'erence in the size of the spores or cells already 
mentioned, those from yeast being the larger and more nearly 
spherical, with a greater number of reproductive spores, that 
is, cells with a single, clear, nucleated cell in their interior, 
while others are filled with a darker granular matter, and 
having only a slight tendency to coalesce or become fila- 
mentous, while the achorion are for the most part ovoid 
and very prone to coalesce and produce elongated cells 
or torulse. Now, with reference to the slight difference 
in size, we must look upon this as a matter of very little 
importance; for to the presence of light in the one case, 
and its almost total exclusion in the other, this difference, 
I have no doubt, is almost entirely due. It would be 
more trustworthy if comparisons of this kind could be made 
at the same stage of development ; for be it remembered that 
yeast obtained from a brewery is in a more favorable state, 
inasmuch as it is stopped at a certain stage of growth or de- 
velopment, and then set to begin its fermentation over again 
in fresh supplies of a new pabulum, which gives increased 
health and vigour to the plant ; while, on the other hand, the 
achorion, or favus fungus, is obtained and used in an ex- 
hausted state from an already ill-nourished or starved-out 
soil. Neither can we attach much importance to differences 
of size and form of the spores, for even this occurs in yeast 
ferment ; and although the ovoid is most frequently seen in 
achorion, it is equally common to yeast when exhausted. 
This is strikingly exhibited in PI. IV, fig. 2, a drawing made 
from a drop of exhausted yeast taken from porter; here we have 
the oval and elongated cell with torulse. To ensure success 
in these and similar experiments, the fungus or yeast should 
be left floating on the surface of liquids ; the process is either 
carried on very slowly or is entirely arrested by submersion. 
Turpin and others, in their experiments on yeast, noticed 
