A cytological study of the egg of Cumingia with special reference etc. 253 
Figs. 30 & 31. Later prophase and early metaphase stages of the first 
cleavage spindle, showing respectively the origin of the chromosomes from the 
nuclear reticulum, and the definitive chromosomes of the first cleavage charac- 
terized by their long irregulär thread-like form and knobbed ends. 
Fig. 32. Several typical chromosomes from the equatorial plate of the 
first Segmentation spindle. 
Fig. 33. Blastnla stage, showing Segmentation spindle at metaphase. A 
centrosome in the shape of a single slightly chromatic grannle has reappeared. 
Fig. 34. Equatorial plate of chromosomes of blastnla stage to show their 
short rod-shaped character in the later cleavage mitoses. 
