Fig. 10 Pure F. majalis, seven days old. Belongs to same series as embryo of 
fig 9. Shows absence of the first crop of head chromatophores; also characteris- 
tic shape of black yolk chromatophores. X 25. 
Fig. 11 F. majals egg hybrid, six days old. Shows shape and arrangement 
of yolk chromatophores. 19. 
Fig. 12 Pure F. majalis, six days old. Shows the absence of yolk chromato- 
phores on the part of the yolk away from the embryo. Many chromatophores near 
the embryo were not drawn as they were much obscured by the yolk globules. X19. 
Fig. 13 Pure F. heteroclitus, four days old. There were no blood vessels 
near the cells figured. Shows characteristic early chromatophore group, before 
they have migrated onto the blood vessels. Embryo same stage as fig. 2. & 114. 
Fig. 14 F. heteroclitus egg hybrid, four days old; has good circulation. Em- 
bryo same stage as fig. 2. Shows characteristic group of yolk chromatophores on 
the side of the yolk sac, oppcsite to the embryo, where the blood vessels have just 
become established. 114. 
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