On the Effect of Centrifugal Force on the Frog’s Egg. 
By 
J. F. McCleudon 
(From the Histological Lahoratory of Cornell University Medical College, New York City, U.S.Ä.) 
With 9 figures in the text. 
The centrifuge has become a populär piece of apparatus for the 
analysis of the structure and developmental processes in the animal egg. 
The resiüts thus obtained are very interesting, but the Interpretation of 
these results have been divergent in some cases. Therefore it may be 
of interest to consider certain facts that have a bearing on the disputed 
points. 
On the Cytoplasmic Structure. 
In a recent paper, Gurwitsch (09) maintains that centrifugal force 
destroys the alveolar structure of the frog’s egg by separating the Con- 
tents of the alveoles, enchylemma, as a layer at the animal pole, from 
the substance forming the walls of the alveoles, hyaloplasm, which then 
forms a layer just below the enchylemma. Gurwitsch had reported 
the Observation before the Anatomische Gesellschaft at Jena in 1904, 
and similar results were published by Koxopacka (08), with this diffe- 
rence that Gurwitsch, following the alveolar theory of Butschli, called 
the substance that rises to the top of the egg enchylemma, whereas Kono- 
PACKA, adhering to the reticular theory of Leydig used the term hyalo- 
plasm to denote the same substance. In order to throw light on the 
question whether the alveolar structure is destroyed by centrifugal force 
I have made a study of the cytoplasm of the normal egg. 
A small portion of a thin smear of the Imng ovarian egg of Rana 
'pipiens is shovTi in fig. la. The large ovals represent yolk-platelets, the 
black dots pigment, and the small circles represent spheres of a sub- 
