158 



BERTRAM G. SMITH. 



in the first cleavage stage ; observations on the rate of deposition 

 of silt on their envelopes indicated that they had been laid dur- 

 ing the preceding night or late in the afternoon of the day before. 



10 



11 



12 



13 



14 



15 



FIGS. 4-15. Early segmentation stages of eggs of Cryptobranchus. Freehand 

 sketches from living material magnified about \ diameters. 



FIG. 4. Egg found September 7 at 10 A. M., sketched at I P. M. The first 

 cleavage line extends over exactly half a circumference. 



FIGS. 5-7 show variations in the second cleavage. Fig. 5, egg laid September 6 

 at about 6:30 P. M., sketched September 7 at 3 P. M. ^igs. 6 and 7, eggs found 

 September 7 at 10 A. M., sketched at 1:30 P. M. 



FIG. 8. Egg laid during night of September 7-8, sketched September 9 at 5:30 

 A. M. 



FIGS. 9-11. Variations in third cleavage. Eggs laid during night of September 

 7-8, sketched September 9 ; Fig. gat 3:50 A. M., Fig. 10 at 2:30 A. M., Fig. II 

 at 5:30 A. M. 



FIG. 12. Egg laid during night of September 7-8, sketched September 9 at 5:45 

 A. M. 



FIGS. 13 and 14. Fourth cleavage stages. Fig. 13, a later stage of egg repre- 

 sented in Fig. 8, sketched September 9 at 8 A. M. ; Fig. 14, a later stage of egg rep- 

 resented in Fig. 9, sketched September 9 at 8 A. M. 



FIG. 15. Egg found September 7 at 10 A. M., sketched September 8 at 8:45 A. 

 M. Four nearly equidistant cleavage lines reach almost to the center of the lower 

 pole. 



