7 



of the different stages for sections. There is no visible 

 fertilization-ir.eiTibrane Riven off after i-he Denetration of the 

 snermatozoa. 



CLEAVAGE. 



Cleavage is total, equal and nearly regular, esnecial- 

 ly in the early stages. The divisions occu:- at short inter- 

 vals, and the blastorr.eres soon move away fro:r; the center 

 of -he egg, thus foriTii-^g a gradually enlarging segmentation 

 cavity. The cells continue to divide and arrange themselves 

 into a single layer around the blastocoele to forin a true 



no 



tative oole as the deutor laclm and Dfotoolasp are distributed 

 evenly in all carts. But as is custcxary and for convenience 

 of descriDtion I v/ill call the oart of the ovum froin which 

 the GOlar bodies are given off the unoer oote, and the Dart 

 of ohc egg OD osite che lov;er Dole, 



The first cleavage occurs a short tirr.e after the oolar 

 bodies are e.iected. The Diane of division is vertical; the 

 segmentation-furro'iv begins at the upoer pole and gradually 

 deepens ur.til the egg is cut into two equal parts. The egg. 



