THE OVUM 37 



FIG. 7 Fid. 8 



Semidiagrammatic representation of the processes of cell and nuclear division 

 (karyokinesis) in Ascaris megalocephala. (After Kostanecki.) 



FIG. 2. Resting cell. 



FIG. 3. Division of centrosome. 



FIG. 4. Prophase centrosomes at the 'poles; radiation well-developed; 

 chromatin net-work broken up into four chromosomes. 



FIG. 5. Mother-star stage (monaster); chromosomes arranged at the 

 equator. 



FIG. 6. Metaphase; the longitudinally divided chromatin filaments moving 

 toward the poles. 



FIG. 7. Anaphase; beginning of division of cell body. 



FIG. 8. Division of cell body almost completed; the central spindle shows 

 the beginning of the intermediate bodies. 



the ovum the head and middle-piece, representing 

 the nucleus and centrosome, respectively, of a cell 

 from the testicle (the male organ, the cells of which 

 secrete the spermatozoon) form eight chromosomes. 

 The chromatin of the germinal vesicle of the ovum 

 also forms eight chromosomes. The process continues 

 within the cell until thirty-two chromosomes are de- 

 veloped by longitudinal cleavage; these are subdivided 

 into sixteen chromosomes, which enter each diaster or 

 daughter cell. 



