312 D. H. TENNENT. 



(b) Observations on Eggs Treated ivith C0 2 . 



Due precautions were of course taken to avoid chance fertiliza- 

 tion. The control showed freedom from segmenting eggs. 



In the sections of these eggs it was even more difficult than in 

 the fertilized eggs to determine accurately the number of chro- 

 mosomes. Sections thick enough to contain all of the chromo- 

 somes were unintelligible. Thinner sections were likewise of 



a b 



Fig. 9. a-b. Sections through same equatorial plate C0 2 egg. 



little value. Fig. 9 shows all of the chromatic material con- 

 tained in the equatorial plate as demonstrated in two sections of 

 this egg. The impossibility of stating with any reasonable de- 

 gree of accuracy the number of chromosomes involved is evident 



t" . 



^ r </ 



Fig. 10. a-d. Four longitudinal sections through 1st segmentation spindle, 

 late anaphase. C0 2 egg. Spindle fibers omitted. 



to any observer. Nor is the situation appreciably relieved by 

 the examination of longitudinal sections of the spindle in later 

 anaphase. 



In such sections as those shown in Fig. 10, a-d, a cursory 



