154 SMALLU'OOD. 



some of the first polar spindle gives rise to the cortical zone of 

 the second polar spindle. The central corpuscle of the cen- 

 trosome of the first polar spindle gives rise to the centrosome 

 of the second polar spindle. Thus we may say that the cen- 

 trosome of the first polar spindle in Bulla solitaria not only 

 gives rise to the centrosome and mitotic figure of the second 

 polar spindle, but to the cortical zone or outer sphere substance 

 surrounding each centrosome. 



ALLEGHENY COLLEGE, 

 October, 1900. 



