64 



PROTOPLASMIC CONSISTENCY AND CELL DIVISION 



remained open. The cleavage furrow continued its course beneath 

 the hole leaving an outer margin as a bridge of protoplasm which 

 connects the two blastomeres (Fig. 10 b,c). After several divisions of 

 the egg the bridge thinned down in its middle until it broke through 

 and the resulting strands were gradually drawn into the blastomeres 

 from which they had projected. 



6.00 



6.12 



8.00 



7.10 



10.00 



Fig. 11. Effect on an Arbacia ovum of a deep cut which persisted. For des- 

 cription of the results see text. Pigment granules collect in plane of original 

 furrow. 



Experiment 6. — (Fig. 11.) This experiment was performed on an 

 Arbacia egg. An incomplete cut was made almost perpendicular to 

 the cleavage furrow but to one side of the daughter nuclei. The furrow 

 on the side away from the daughter nuclei became obliterated (Fig. 

 11a). On the other side it continued its original course resulting in 

 the pinching off of the nucleated Blastomere a (Fig. 11 b). The 

 nucleus in the remainder of the egg shifted its position only shghtly and 



