F 
240 N. M. STEVENS, On the ovogenesis and spermatogenesis of Sagitta bipunctata. 
Figs. 29—30. Stages showing the shortening of the loops to a 
dumb-bell form. 
Figs. 31—33. Different phases of the first maturation division; 
Fig. 32 polar view of the equatorial plate showing nine chromo- 
somes. 
Figs. 34-36. Different phases of the second maturation division. 
Figs. 37—39. Stages in the formation of the spermhead, or 
spermatid from the nine chromosomes of the second maturation di- 
vision. 
