1895.] Embryology. 387 
Since this cytrotropic state seems to vary in any cell it may play a 
varying and not unimportant part in the phenomena of ontogeny. 
ells may, at time unite, at another, remain 
y 
separate. Migrations of cells towards oxygen on the surface of the egg, 
etc., would also be exhibitions of these same cytrotropic powers. 
