76 KANSAS UNIVERSITY QUARTERLY. 



turation division, a portion of the nucleus buds ofP, and, passing 

 through the cytoplasm, is extruded from the cell. This is the itomere. 



12. The protrusion and casting out of the itomere is accompanied 

 and succeeded by the formation of yolk masses and by a great increase 

 in the size of the cell. 



13. The pathway left by the itomere, on its passage through the 

 cytoplasm, persists and becomes stronger as the cell advances in de- 

 velopment. It marks out the course later taken by the axial filament. 



14. The axial filament is not formed by an elongation or outgrowth 

 of the centrosome, but by the condensation of the cytoplasmic re- 

 ticulum, along the line marked out by the itomere in its passage to 

 the cell wall. 



Laboeatoet of Zoology and Histology, 

 University of Kansas. 



