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The Nucleus of the Yeast Plant. 
THE NUCLEUS OF THE YEAST PLANT. 
On the Structure and Biology of the Yeast Plant (Saccharomyces 
Cerevisiae). By Fred Mutchler. Journal of Medical Research, 
Vol. XVI., Nov., 1905. Boston. 
O N account of the diversity of opinion which exists regarding the 
nucleus of the yeast plant, attention may be drawn to the 
results embodied in the above contribution, which appears in a 
journal not generally read by botanists. 
The first part of the paper enters into the consideration of the 
structure of the yeast cell. The cytoplasm is more or less reticulated, 
vacuolated or areolated, the meshes are very close and the areolation 
is much more regular than in the animal and vegetable cells studied 
at the same time and prepared in a precisely similar manner. 
The nucleus occupies the centre of the cell and is relatively 
larger than any other part. The measurements given are surprising ; 
the average diameter of the cell itself is given at seven microns, and 
of the nucleus, five microns. The nucleus is closely areolated with 
a fine net-work which exhibits a great affinity for gentian violet. 
Surrounding the nucleus is a distinct nuclear membrane, and 
in close association with it are a varying number, from six to ten, 
of small, but definite, granules. Sometimes these may be scattered 
throughout the cell but usually are situated “ immediately under 
the membrane.” 
No evidence of karyokinesis has been observed, and it is 
believed that the division of the nucleus in all cases is direct. 
The second portion of the article deals with the effect upon the 
cell of various substances which included a large number of metals, 
formalin, hydrogen peroxide, acetic, picric, and other acids, alcohol, 
and, finally, many anaesthetics. 
The conclusions drawn from these experiments are as 
follows :— 
(i.) The form of Saccharomyces Cerevisiae, having remained 
constant under the conditions imposed, leads to the conclusion that 
it is not a variable species. 
(ii.) Any variation in form is due to the inherent nature of 
the cell rather than to external conditions. 
(iii.) Variation in the size and in the rate of growth of the 
cells is readily produced by changes in the conditions under which 
they grow. 
(iv.) Anaesthetics do not permanently destroy the growth or 
reproduction of this species. 
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