1 70 



FERTILIZATION 



Van der Waals' forces, 137, 140; 



radii, 140. 

 Vapour pressure of egg contents, 



81. 

 Viscosity, of cytoplasm, 94-97 ; of 



egg homogenates, 98. 

 Vitelline membrane, 8-12, 115. 

 Volume changes, in eggs, 5, 18-20, 



80-81. 



Weil Felix reaction, 139. 



Yolk protein synthesis, 62, 76-78. 



degradation, 76-78. 



Young's modulus, of cortex, 93, 95. 



Z. See Sperm-egg collision fre- 

 quency. 



^-potential, of eggs, 134; of sperma- 

 tozoa, 30. 



Zona pellucida, 5, 12, 11 4- 115; 

 block to polyspermy in, 1 14-1 15 ; 

 effect of cold-shock on, 115. 



Zone phenomenon, 29. 



