CHAPTER V.—COMPARATIVE REVIEW.—DOUBTFUL ASCOMPCETES. 271 
opinion. They have shown that the earlier observers obtained uncertain results 
from having different and imperfectly distinguished forms mixed up together in 
their impure cultures, and have revealed another source of obscurity in their belief 
that every form of sprouting Fungus must be regarded as an inciter of fermentation 
or ‘Yeast-fungus,’ and conversely that all alcoholic fermentation was caused by the 
vegetation of a sprouting Fungus resembling Saccharomyces. We know now that 
this is not so. 
But there are j7s of all many species of Fungi in which the,only mode of vegetation 
is by sprouting or which vegetate in this way under certain circumstances or in certain 
stages of their development. Foremost among these are the ascogenous species of 
Saccharomyces. Connected with the latter are the forms which resemble them 
exactly in their vegetative construction, but in which asci and distinct spores are not 
known, or it should be said perhaps are not yet known. These are usually, and for 
the present rightly placed in the genus Saccharomyces ; whether they really belong 
to it has yet to be ascertained; Among them are S. apiculatus which has been 
so thoroughly examined by E. Hansen, and ‘Pasteur’s Torulae’ recently investi- 
gated by the same observer. To these must be added Exoascus, also the plants 
mentioned above on page 114 as examples 
of germination by sprouting, and certain 
Mucorini (see page 155) with further in- 
stances in the Ustilagineae (see page 179), 
Tremellineae, and Exobasidium recently A 
supplied by Brefeld (see section XCII). 
Lastly, we must mention Fumago (see 
page 249) on Zopf’s authority, and a form 
most probably nearly related to Fumago 
or Pleospora and at present imperfectly 
known, which I formerly described as x 
Dematium pullulans. It is very com- 
mon on the surface of plants; and for 
this reason and because its sprout-cells 
are very like those of some species of 
Saccharomyces the two forms have no 
doubt often been mistaken for one another EEE BEER NER oe ert 
by earlier observers, who did not distin- of cells with brown membranes forming tubes and occasionally 
= “ & sprouts in a saccharine solution. 2 portion of a filament 
guish different forms very acutely. It is vegetating in a saccharine solution and covered with sprout- 
probable that a similar confusion is at the el. 4 magn. 390, 2 nearly zoo times. 
bottom of Pasteur’s statement, that certain 
brown-walled cells which are found on succulent fruits are the resting-states of 
species of Saccharomyces which excite fermentation. It will be well therefore to 
repeat here my former description of the plant which has been confirmed by Löw 
(see Fig. 123). 
Small ellipsoid cells sprout in large quantities in a saccharine solution or in water 
from the colourless branched and septate mycelial hyphae of Dematium, some from 
the extremities of short branches, some from their sides. They are abscised and 
multiply in exactly the same way as the cells of Saccharomyces. Finally, when the 
available food is exhausted, the mycelial hyphae divide by transverse walls into cells 
which are as long as broad and then swell into a roundish shape ; their membranes 
also become thick and two-layered and of a brown colour, and they secrete small drops 
of oil in their interior. The free sprout-cells show the same changes under similar 
conditions. When they are again placed in a suitable fluid, each brown cell goes 
through a period of rest, and then puts out a germ-tube, which proceeds to abscise 
fresh cells either at once or after it has developed into a branched hypha. The 
sprout-cells of Dematium attain a considerable size and then become of an elongate 
& 
& 
ce 
