Note 112 — Chapter V

R. Lillie has recently shown that in a hypotonic solu­tion water diffuses more rapidly into a fertilized than into an unfertilized egg. This is exactly what one should expect since the unfertilized egg is not only surrounded by the cortical layer but also by a thick layer of jelly both of which are lacking in the fertilized egg. It is difficult to understand how this observa­tion can throw any light on the mechanism of development, since water diffuses rapidly enough into the unfertilized egg.