August 6, 1870.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
103 
to obtain the result another experimenter declares he 
lias obtained, wliile want of skill and care in the 
execution of difficult experiments are sufficient to 
cause discrepancies; but I believe that I have not 
neglected any precaution, and moreover Professor 
Nageli, to whom I gave a mixture prepared exactly 
according to Pasteur’s directions, has not been more 
successful than I was. 
Considerations of another kind induced me to dis¬ 
continue these experiments without losing more time 
over them.* 
It must be noticed that, although Pasteur weighed 
the deposit formed in his experiments, he has not fur¬ 
nished any evidence that the 43 milligrams obtained 
was true beer-yeast. He should have brought that 
deposit into contact with sugar-water, to show that 
it really consisted of Torvula cerevisia, and it should 
have caused sugar to ferment. The microscope is a 
very untrustworthy instrument for determining the 
real nature of such things as this. To judge from 
the proportionately large quantity of lactic acid 
formed from sugar in Pasteur’s experiments, the 
seeds of Torvula cerevisice must have given rise to 
lactic ferment, viz. Penicillium glaucum, and the de¬ 
posit must have consisted of this. 
It is surprising that Pasteur claims to have pro¬ 
duced beer-yeast in mixtures that did not contain 
any sulphur. There is no such thing as beer-yeast 
that does not contain sulphur ; its chief constituent 
is a nitrogenous substance containing as much sul- 
phur as casein does, or even more. 
Neither sugar nor tartrate of ammonia contain 
sulphur, and even yeast ash is generally free from 
sulphur. That which I used did contain a trace of 
sulphuric acid, but even if it had contained a consi¬ 
derable amount, the assumption that the yeast plant 
possessed the capability of decomposing sulphuric 
.acid would have been admissible only if it had been 
distinctly proved that true beer yeast could have 
heen produced in Pasteur’s mixtures. I look for¬ 
ward to this proof with the greatest interest, and, if 
Pasteur should succeed in obtaining it, we shall have 
gained an exceedingly important piece of information 
in reference to plant physiology, either that there is 
beer yeast not containing any sulphur, or that fungi 
iiave the power of decomposing sulphuric acid, and of 
producing an albuminate from its sulphur, together 
with ammonia and the elements of sugar or tartaric 
acid. This is a power which has hitherto been re¬ 
garded as belonging only to green plants under the 
influence of light. 
The fact that Pasteur, in determining the ammo¬ 
nia in his fermented mixtures, found less than he 
had added to them, cannot possibly be relied on as 
-evidence that tliis ammonia served as food for the 
growth of yeast; for I must again point out, that in 
no single instance has he shown the formation of 
true yeast or its increase to be due to the pre¬ 
sence of ammonia in the fermenting liquid.f 
* It is well known that in ammoniacal salts of organic acids 
there is often a spontaneous decomposition accompanied by 
formation of mould, without any addition of ferment. 
f My late friend Pelouze communicated to me, some nine 
years since, the results of Pasteur’s investigations, and I then 
remarked to him, that I did not perceive anything to induce 
alteration in my views respecting the cause of fermentation, 
—adding, that if it were possible, by the aid of ammonia, to 
produce yeast in fermenting liquids, or to increase its quan¬ 
tity, this possibility would soon be turned to account, and 
that I would await such a result; but, up to the present | 
time, the industrial preparation of yeast has not altered. 
In carrying out the plan adopted by Pasteur for 
separating ammonia from fermented liquids by boil¬ 
ing them with calcined magnesia, I have repeatedly 
obtained less ammonia than the liquid contained; 
but, in such instances, the deficiency of ammonia 
was recognizable in the residual magnesia having 
formed ammonio-phosphate of magnesia in conse¬ 
quence of the presence of soluble alkaline phosphates, 
which are never wanting in fermented liquids. 
Pasteur has also discussed the question as to 
what becomes of the nitrogen of yeast in fermenta¬ 
tion ; he says, “ In vinous fermentation there is not 
the slightest formation of ammonia at the expense 
of yeast.” * Tliis statement is, however, incon¬ 
sistent with that on the previous page, to the effect 
that a litre of water, containing the soluble consti¬ 
tuents of yeast, yielded '038 grm. of ammonia. I 
find, moreover, that all fermented liquids contain 
ammonia, though certainly a very minute quantity. 
It seems as if nitrogen were excreted in some other 
form, partly, perhaps, as organic bases. I have 
been unable to detect leucin in the fermented residues, 
probably because its amount is too small. Ludwig 
has found trimetliylamin in all the varieties of wine 
examined by him; and Oser, likewise, has described 
a very remarkable nitrogenous base, destitute of 
oxygen, as being a constant product of the fermen¬ 
tation of sugar with yeast. According to liis expe¬ 
riments, tliis base appears to be a constant product 
of the fermentation of cane sugar. 
In the wine districts of France, where many 
thousands of gallons of wine are distilled in the ma¬ 
nufacture of brandy, the residues of this operation 
would probably be a rich material for investigation, 
in regard to the non-volatile products of fermentation, 
and they would probably constitute a source of in¬ 
teresting discoveries. Moreover, if it be the case, 
as Pasteur states, that for each litre of alcohol pro¬ 
duced in fermentation, there is also formed 50 grm. 
of glycerin, it is possible that glycerin might be ex¬ 
tracted from these residues with advantage. 
Recent researches on the causes of fermentation 
and putrefaction have been prosecuted essentially 
under the influence of the ideas—entertained by 
Turpin, Cagniard-Latour, Mitsclierlicli, and others 
—which prevailed in the minds of many physiolo¬ 
gists thirty years ago and have been recalled by 
Pasteur within the last ten years. 
Turpin states, as the result of liis microscopic in¬ 
vestigation of beer fermentation and acetous fermen¬ 
tation, that “ under fermentation is to be understood 
a joint action of water and living bodies which feed 
and develope by the assimilation of a constituent of 
sugar, while, at the same time, eliminating from it 
alcohol or acetic acid ; a purely physiological action 
that commences and ends with the existence of in¬ 
fusorial plants or animalcules whose life ceases only 
when the nutritive saccharine materials are totally 
exhausted.”! It is impossible to detect any diffe¬ 
rence between the fundamental views of Turpin and 
those of Pasteur. 
Inasmuch as Pasteur has again diverted the 
study of fermentation and putrefaction by micro- 
scopists into the old objectless path, the result has 
been, that the general aspect of these processes has 
been disregarded, the phenomena that are common 
to all of them have been overlooked. Observation 
* Page 380. 
f Arm. Cliem. Pliarm. 1839, xxix. 100. 
