KGGS OF ARBACI A PUNCTULATA 



453 



Oil 



Nucleus 

 Clear layer 



— Mitochondria 



White Half 

 2 



White Half 



(recentrifuged) 



3 



cy.:-:rX — Y°ik 



Granular Quarter 

 5 



— Pigment 



Whole Egg 



(centrifugedj 



I 



Red Half 

 6 



Red Half 



(recentrifuged) 



7 



Pigment Quarter 

 9 



Fig. 159. Unfertilized egg of Arbacia punctulata, stratified by centrifugal 

 force (about 3 min. at 10,000 g.), and the halves and quarters into which it 

 breaks. Drawn from camera lucida sketches and photographs, as accurately as 

 possible to scale (magnified X275). The clear area in 7 at the centripetal pole 

 is due to further packing of the granules with longer centrifuging. From 

 Harvey (1936) 



