July 23, 1870.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
G3 
3 r east gave ’685, in another case ‘568,* and a third 
*387 per cent.f The amount of ash also varies in 
yeast; it averages from 7 to 8 per cent., and con¬ 
tains much phosphate of lime, which is evidently in 
a state of combination similar to that in cereal grain, 
for it cannot be extracted by washing. 
Two samples of yeast-asli gave the following re¬ 
sults :— 
I. 
II. 
Mitscherlieh. 
Phosphoric Acid. . . 
44-76 
48-53 
59-3 
Potash. 
29-07 
30-58 
28-3 
Soda. 
2-46 
Lime. 
Magnesia. 
2-39 
4-09 
2-10 ) 
4-16 J 
[ 12-5 
Silica. 
14-36 
Chlorine, Carbonic Acid, 
Peroxide of Iron . . 
| 2-12 
- 
These are the same constituents 
, and nearly the 
same proportions, as in the ash of wheat and rye; 
after deducting silica, they are the same as in the 
asli of barley. Other fungi, such as truffles and 
the morel, contain a larger amoimt of potash. | 
Tuber cibarium. Morchella esculenta. 
Phosphoric Acid . . 
32-96 
39-03 
Potash. 
54-51 
49-51 
Lime and Magnesia . 
22-83 
18-48 
Sulphuric Acid . . 
1-17 
2-98 
The deficiency of sulphuric acid in yeast-asli is 
remarkable; probably it is explained by the prepon¬ 
derance of phosphoric acid. The ash of ordinary 
champignons (Agaricus campestris ) contains 24'29 
per cent, of sulphuric acid, and only 15'43 per cent, 
of phosphoric acid.§ 
Fungi live as parasites on organic substances pro¬ 
duced in the organism of other plants. Their spores 
liave the same relation to the dead plants or animal 
remains, and to solutions containing their chief con¬ 
stituents, as the blossoms of annual plants (cereals, 
for instance), which have collected in the growing 
seeds, the substances contained in the leaves, stem, 
and roots. Just in like manner the protein substances, 
phosphates, etc., still remaining in the dead plant- 
remains, are transferred into the developing fungi, 
and acquire the form of albumin, legumin, sugar, 
mannite, cellulose, etc., by the influence of the or¬ 
ganic action of the fungi. In decayed oak-wood, 
Sclilossberger|| found scarcely a trace of phosphates, 
while the parasitic fungus [Dcedalea quercind) grow¬ 
ing on it contained a considerable amount. The in¬ 
stability of yeast when kept is well known : when 
left in a moist, pasty state, in a cool place, evolution 
of gas sets in. This gas is carbonic acid free from 
nitrogen. In the pasty yeast funnel-shaped hollows 
are formed, from which the gas escapes as from a 
crater; most of it, however, dissolves in the water, 
and evaporates with this. When the temperature 
of the moist yeast is raised, the evolution of gas is 
more marked; a froth is formed on the surface of 
the liquid, and the transformation of the yeast is 
accelerated. Even at 30° or 35° C. a true and al¬ 
most violent fermentation takes place, just as in a 
solution of sugar that is mixed with sufficient yeast, 
and tliis evolution of gas goes on till the fermenta¬ 
tion is ended. 
. Besides carbonic acid, this yeast fermentation 
yields another volatile product, viz. alcohol. This 
* Reiclienbach. + Demp wolff. 
I O. Koklrauscli. § Ibid. 
II Ann. Cli. et Ph. lii. 115. 
lias been observed by both Pasteur and Becliamp. 
Pasteur has also found that when very little sugar is 
fermented with a great deal of yeast, more alcohol is 
obtained than corresponds to the sugar, and hence 
he inferred that alcohol must be produced from the 
yeast. Pasteur explains this phenomenon as fol¬ 
lows:—“The beer-yeast consisting almost entirely 
of cells that have attained their normal develop¬ 
ment, or are, so to speak, full grown, is brought in 
contact with sugar, its life is renewed,—it sprouts. 
Tliis is a well-known fact. If the liquor contains 
sugar enough, the buds develope; they assimilate 
sugar, and the albuminous material of the mother 
cells. In this way they gradually attain a certain 
bulk. This is a true picture of ordinary fermenta¬ 
tion. If, on the contrary, we suppose the sugar to be 
insufficient for converting the first shoots into per¬ 
fect cells, or even into fully-formed visible cells, tliis 
has to be done in some way with mother-cells; and, 
since external food fails, the young buds live at the 
cost of the mother-cells.” 
He explained the fermentation of yeast itself thus: 
The life of yeast manifests itself as soon as its con¬ 
ditions, moisture and warmth, are suitable. Like a 
seed always ready to germinate, yeast lives when it 
has the requisite temperature and water, at the cost 
of its own substance, and its vitality manifests itself 
by the physiological act peculiar to it,—the formation 
of carbonic acid, alcohol, succinic acid, and glyce¬ 
rine. If this yeast be brought in contact with 
sugar, its vitality, which is never interrupted, con¬ 
tinues; but in tliis case it completes its formation 
with a very much greater apparent energy, because 
in the same time life and organization have much 
increased.” 
I must confess that I am not able to form a clear 
conception of Pasteur’s view as to the cause of the 
fermentation of sugar and yeast as represented in 
the foregoing passage. He has enriched the history 
of fermentation with a number of interesting facts, 
but in regard to the cause of the breaking up of 
sugar, our insight into the matter has not been 
thereby increased. 
It can scarcely be doubted that the yeast developed 
in fermenting beer-wort consumes a certain quantity 
of sugar for the formation of its cell-membrane ; but 
it remains wholly unintelligible how the conversion 
of sugar into cellulose—of one carbon hydrate into 
another with less water—can induce the breaking 
up of another part of the dissolved sugar. 
In one of his experiments, Pasteur mixed a solu¬ 
tion of 9'899 grm. sugar with 20 c.c. of a clear watery 
solution of yeast and a trace of yeast. The liquid 
fermented, and the yeast added to it as a seed in¬ 
creased considerably. After the sugar was com¬ 
pletely decomposed, the yeast was weighed, and it 
amounted to 152 milligrams. According to Pasteur, 
yeast contains on the average 18"5 per cent, cellu¬ 
lose. Substituting for this 20 per cent, of sugar, 
there would have been 9869 milligrams of sugar de¬ 
composed in tliis case, and 30 milligrams of sugar 
consumed for the production of yeast. But it is 
scarcely possible to think that the physiological act 
of transformation of 30 milligrams of sugar into the 
substance of the cell-membrane of the yeast can 
have been the cause of converting 329 times as 
much sugar into carbonic acid and alcohol, or suc¬ 
cinic acid, glycerin, and carbonic acid products, 
which take no further part in the vitality of the 
cell. 
