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SELECTED ARTICLES. 
has led me to perceive that the granules of which it is 
composed have a globular form, and to conclude that they are 
probably organized bodies.* 
These bodies are in general simple, diaphanous, spherical 
or slightly oblong, and nearly colorless; — but with all the 
attention I have been able to bestow upon them I have not 
been able to perceive any motions which could be considered 
as external exertion of the will. On the other hand, the glo- 
bules of the yeast, as I have frequently observed, may appear 
in a liquid where they could not be perceived previous to the 
vinous fermentation taking place. When bodies of a globular 
form, other than crystals, are produced in a mucous liquor 
and do not appear to be possessed of the power of locomo- 
tion, these bodies are commonly considered as vegetables. 
We may then consider it as very probable that the globules 
of yeast are organized, and that they belong to the vegetable 
kingdom; these conjectures appear to be confirmed by several 
of the observations which will be noticed subsequently. 
But these plants, if we can so call simple vesicles, are ex- 
tremely small; for among the globules of different dimensions 
of which the yeast is composed, the diameter of those which 
appeared to have attained the final extent of their develope- 
ment, does not commonly surpass the one-hundredth of a 
millimetre; besides they are for the most part below this size, 
* It is now more than twenty-five years since, being engaged in re- 
searches upon the best means of obtaining alcohol by the fermentation of 
different grains, I had the curiosity to examine the fresh yeast by means of 
the microscope. The instrument which I then used was very imperfect ; 
I at that time thought that yeast resembled very fine sand composed of 
crystalline grains, but it is now evident that this was an error. 
The principal microscopical observations indicated in the present paper, 
were made with a microscope constructed by M. Georges Oberhauser. 
The powers which I commonly used were three or four hundred diameters. 
To measure the size of the globules, I introduced into the instrument a 
micrometer, constructed by M. Charles Chevalier ; I will add that this 
optician placed at my disposal one of Amici's microscopes, by which, in 
some instances, T was enabled to examine the globules with higher mag- 
nifying powers. 
