I5O MARY J. GUTHRIE AND HOPE HIBBARD. 



DESCRIPTION OF PLATES. 



Figs. I to 12 and Fig. 24 were made from camera lucida sketches of living eggs. 

 A pantograph was used to enlarge them two and one half times, and this gave a 

 magnification of 1,050 diameters. Tln-y have been reduced one half in reproduc- 

 tion so that the magnification is now 525 diameters. 



Figs. 13 to 23 were made from camera lucida drawings of mounted sections 

 which were enlarged two and one half times and reduced one half giving a final 

 magnification of 725 diameters. 



EXPLANATION OK PLATE I. 



FIG. i. Fertilized egg. 



FIG. 2. Incomplete 2-celled stage. 



FIGS. 3 and 4. 2-celled stage. 



FIG. 5. Polar view of 4-celled stage. 



FIG. 6. Incomplete 8-celled stage. 



