ZOOLOGY: E. G. CONKLIN 
87 
for hydrochloric acid presented in this article are 0.795, 0.844, and 0.945. 
The value (0.738) for potassium chloride at 0.1 molal is again much 
smaller (namely about 14% smaller) than the conductance-ratio (0.861). 
A more complete description of this research will soon appear in the 
Journal of the American Chemical Society. The preparation of the cells 
so as to secure constancy and reproducibility of the electromotive force 
values, the methods of making the measurements, the full experimental 
data, and thermodynamic calculations from them of other free-energy 
values will be there presented in detail. 
This research has been carried on with the cooperation of Prof. A. A. 
Noyes and with the aid of a grant made to him by the Carnegie Institu- 
tion of Washington. The preHminary experiments were made jointly 
with Dr. Louis Weisberg, and the final measurements with Mr. Frank 
W. Hall. For all this assistance I wish to express my great indebtedness. 
1 Lewis, Proc. Amer. Acad., 43, 259-293 (1907); Zs. physik. Chem., 61, 129-165 (1908). 
2 Jahn, Zs. physik. Chem., 33, 545-576 (1900). 
3MacInnes and Parker, /. Amer. Chem. Soc, 37, 1445-1461 (1915). 
EFFECTS OF CENTRIFUGAL FORCE ON THE POLARITY OF 
THE EGG OF CREPIDULA 
By Edwin G. Conklin 
DEPARTMENT OF BIOLOGY. PRINCETON UNIVERSITY 
Read before the Academy, November 16, 1915. Received, January 22, 1916 
If the eggs of the marine gasteropod Crepidula plana are subjected 
to centrifugal force of approximately two thousand times gravity the 
yolk is thrown to the distal or centrifugal pole, the oil and other light 
substances to the centripetal pole, while the nucleus and centrosphere 
together with most of the cytoplasm occupy the middle zone between 
the other two. In eggs centrifuged after fertilization and before the 
first cleavage the yolk zone comprises a little more than three-quarters 
of the volume of the whole egg, the middle zone a little less than one- 
quarter and the oil zone about one sixty-fourth, the relative volumes of 
the three being 49 : 14 : L In normal eggs of this stage the nucelus centro- 
sphere and most of the cytoplasm lie near the animal pole, but in cen- 
trifuged eggs these formative substances may be displaced far from this 
position, the yolk, for example, being thrown to the animal pole and the 
protoplasm to the vegetative pole, or these displacements may take 
place in any other axis. Nevertheless these substances slowly come 
back to their normal positions provided there is sufficient time for 
this before the next cell division. However if cell division intervenes 
