28 



first :iiethod of division. 



ViTierever the second method of cell division occurs, 

 the partition is in one plane, never arched. In all the 

 cases exaiained in v/hich division occurred by the ingrov/th 

 of a cellulose ring, the partition cnt into the central 

 vacuole, so as to cut oifff a segment containing part of the 

 vacuole of the mother cell; in the first method of division 

 however, the segment cut off is at first solid. The rela- 

 tion of the cleavage plci,ne to the vacii.ole seems to deter- 

 mine the method of cell division; in the division of the 

 vegetative cells, where the cleavage pls-ne occurs so as to 

 cut into the solid protoplasmic accumulation in the a,pex 

 of the cell, division talces place "by the first method. 

 ^Vhere the plane of division is sufficiently removed from 

 the a,pex to allov/' the partition to cut into the central 

 vacuole, division is by the second method. 



As mentioned above the nuclei appear to take no part 

 in cell division. This seems to be the rule in coenocytic 

 cells (St , '88), tliough '.Ville lias noted an appa- 

 rent exception in Acrosiphonis ('00). 



The number of nuclei in t}ie smaller daugliter cell just 

 after its formation i.s various. The average number is be- 

 tween 12 and 20, but in some causes, and always following 



