284 BERTRAM G. SMITH. 



EXPLANATION OF PLATE VIII. 



Cryptobranchus allegheniensis. 



FIGS. 39 AND 40. Two successive vertical sections through a nucleus preparing 

 for the fourth cleavage mitosis; almost the entire nucleus lies in these two sections. 

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

 acid. X 400. 



FIG. 41. Another nucleus found in the section used for Fig. 39; early prophase 

 of the fourth cleavage mitosis. X 400. 



FIG. 42. Vertical section through a nucleus in the metaphase of the fourth 

 cleavage mitosis. The fourth cleavage furrow has not yet been formed. Bichro- 

 mate-acetic-formalin fixation; stained with iron-haematoxylin. X 400. 



FIGS. 43 AND 44. Two successive horizontal sections through a newly-formed 

 daughter-nucleus of a fourth cleavage mitosis. The fourth cleavage furrow is 

 newly formed. Bichromate-acetic-formalin fixation; stained with borax-carmine 

 Lyons-blue picric-acid. X 400. 



