58 



PROTOPLASMIC CONSISTENCY AND CELL DIVISION 



protoplasm on each side of the cut merge into a single fluid mass. 

 The nucleus then comes to occupy a central position. Normal 

 mitosis takes place with the fonnation of an amphiaster and cleavage 



3.30 



3.55 



4-.00 



>1-.Z5 



Fig. 6. Effect of a diagonal cut through an Asterias ovum in which the cut 

 brought about a change in the physical state of the egg. a, operation performed 

 at 3.30 p.m. b, 3.35 p.m., original cleavage furrow beginning to be obliterated. 



c, 4.00 p.m., an amphiaster formed in each of the two pieces produced by the cut. 



d, 4.25 p.m., four celled stage in which one cleavage plane was produced by the 

 needle and the other by normal fission. 



proceeds along the equator w^here the boundaries of the two asters 

 are contiguous. 



In the nine cases, in which the original cleavage plane persisted 

 after the cutting process, the semisolid state about the two astral 



