354 WHITMAN AND EYCLESHVMER. 
EXPLANATION OF PLATE XIX. 
All the figures were drawn from material fixed in chrom-osmic and preserved 
in 80% alcohol. Magnification about 16 diameters. 
Fic. 21a. View of the upper pole of the egg, showing the position of the first 
groove and micropylar orifice. 
Fic. 21b. Profile view of the same egg. 
Fic. 22a. View of the upper pole of the egg at the beginning of the second 
vertical cleavage. 
Fic. 22b. Profile view of the same. 
Fic. 23a. View of the upper pole, showing symmetrical third verticals. 
Fic. 23b. Profile view of the same. 
Fic. 24a. View of the upper pole in same stage as Fig. 23, showing an 
asymmetrical position of one of the third verticals. 
Fic. 24b. Profile view of the same egg. 
Fic. 25a. The formation of the first set of circular grooves. 
Fic. 25b. Profile view of the same. 
Fic. 26a. The first set of circular grooves completed, and the fourth set of 
verticals beginning. 
Fic. 26b. Profile view of the same. 
Fic. 27a. Fourth set of verticals well advanced. 
Fic. 27b. Profile view of the same. 
Fic. 28a. Shows the addition of two new sets of circular grooves, one within, 
the other without, the first circular groove. 
Fic. 28b. Profile view of the same. 
Fic. 29a. A little later stage, showing another set of circular grooves outside 
of those seen in Fig. 28. 
Fic. 29b. Profile view of the same. 
Fic. 30a. About the same stage. The cells show a bilateral arrangement. 
Fic. 30b. Profile view of the same. 
Fic. 31a. The lower pole at about the same stage as Figs. 29 and 3o. 
Fic. 31b. Profile view of the same. 
Fic. 32a. A later stage. 
Fic. 32b. Profile view of the same. 
DP. ey 
