ABSTRACT
In recent years many attempts have been made to determine the absolute coefficient of viscosity of “protoplasm.” The values for this constant obtained by different workers differ widely, and while it is probable that the protoplasm from different sources is never the same in its composition, and cannot be expected to be constant in its viscosity, many sources of error in such determinations have not been sufficiently appreciated. One of the most serious of these, the presence of powerful currents in the protoplasm, forms the subject of this communication.
The elevation of this membrane in the healthy unfertilised egg has been questioned by Wilson (1929 and personal communication), though it was described by de Quatrefages (1847, 1848, 1850), and subsequently confirmed by Ziegler (1914) and Faure-Fremiet (1921). Wilson suggests that healthy unfertilised eggs never throw off this membrane, but the experience of the writer does not support this conclusion.
