274 BERTRAM G. SMITH. 



EXPLANATION OF PLATE III. 



Cryptobranchus allegheniensis. 



FIGS. 9 AND 10. Two successive vertical sections through a single daughter- 

 nucleus of the first cleavage mitosis. The sections are nearly meridional, and pass 

 very close to the other daughter-nucleus, hence at right angles to the plane of the 

 first cleavage furrow which is not yet formed. The nucleus shown is almost entirely 

 confined to the two sections. Bichromate-acetic-formalin fixation; stained with 

 borax-carmine Lyons-blue picric acid. X 400. 



FIG. ii. Vertical section through a single daughter-nucleus of the first cleavage 

 mitosis. The section is nearly meridional, and passes very close to the other 

 daughter-nucleus, hence at right angles to the plane of the first cleavage furrow 

 which is not yet formed. A considerable part of each nuclear vesicle is left in an 

 adjacent section, and comparison with these other portions shows that the plane 

 of contact of the two nuclear vesicles is oblique to the plane of the section. Bichro- 

 mate-acetic-formalin fixation;, stained with borax-carmine Lyons-blue picric-acid. 



X 400. 



FIG. 12. Vertical section showing a single daughter-nucleus of the first cleavage 

 mitosis, taken at right angles to the plane of the first cleavage furrow which is not 

 yet formed. The entire double nucleus is confined to this section. Bichromate- 

 acetic-formalin fixation; stained with borax-carmine Lyons-blue picric-acid. 



X 400. 



FIG. 13. Vertical section, parallel to the newly-formed first cleavage furrow, 

 through a single daughter-nucleus of the first cleavage division. Part of the 

 nucleus is left in an adjacent section, where it is likewise distinctly double. Bichro- 

 mate-acetic-formalin fixation; stained with borax-carmine Lyons-blue picric-acid. 



X 400. 



FIG. 14. Vertical section, parallel to the first cleavage furrow, through the 

 other daughter-nucleus of the egg used for Fig. 13. Part of the nucleus is left in 

 an adjacent section, where the two nuclear vesicles are more closely united. Bichro- 

 mate-acetic-formalin fixation; stained with borax-carmine Lyons-blue picric-acid. 



X 400. 



