54 
SELECTED ARTICLES. 
Since then I have frozen by a cold of 5° cent, fresh yeast 
mixed with a certain quantity of water, and afterwards 
ascertained that it could act upon saccharine solution like 
ordinary fresh yeast. 
In conclusion, I may observe, that I have examined the 
principal works which treat of the vinous fermentation, in no 
one of which has it been proposed to employ the microscope 
to study the phenomena upon which it depends.* 
This essay, as we may judge from the researches which it 
exhibits, was useful, since it has furnished many new observa- 
tions, and from which it principally results — 1, that the ferment 
of beer, a ferment of which so much use is made, and which 
for this reason it is proper to examine more particularly, is a 
collection of small globular bodies, susceptible of reproduc- 
tion, consequently organized, and not a substance simply 
organic or chemical, as was supposed; 2, that these bodies 
appear to belong to the vegetable kingdom, and regenerate 
themselves in two different manners; and 3, that they appear 
to act upon a solution of sugar only while in a living state; 
from which we may conclude that it is very probably by some 
effects of their vegetation that they disengage carbonic acid 
from such solutions, and also convert them into spirituous 
liquors. 
I may likewise remark, that ferment, considered as an 
organized matter, perhaps merits the attention of physi- 
ologists on these accounts — 1, that it may be formed and 
develope itself under certain circumstances with great prompt- 
ness, even in an atmosphere of carbonic acid, as in a 
brewer's vat; 2, that the mode of its regeneration presents 
peculiarities which have not yet been observed with regard to 
* Leuwenhoek, in 1680, had already observed by the aid of the micros- 
cope that the yeast of beer contained globules, which he attributed to the 
farina employed for the formation of the must; but this observation, of 
which 1 had no knowledge previous to the presentation of my Memoir to the 
Academy, did not lead the author to the most important point, that these 
globules are capable of germinating and vegetating in the must of beer 
during its fermentation. 
