H 



WALLACE. 



EXPLANATION OF PLATE IL 



Fig. I. Ovum with blastoderm covering 1 of yolk surface. X g. 



Fig. 2. Ovum with blastoderm covering % of yolk surface. X 9. 



Fig. 3. Ovum with blastoderm covering over /-^ of yolk surface. X 9. 



Fig. 4. Ovum with blastoderm covering nearly j{ of yolk surface. X g. 



Fig. 5. Ovum near the time of the closure of the blastopore. X 9. a.d. ^ 

 adhesive disc ; /. = lip of blastopore. 



Fig. 6. Blastoderm of an earlier stage than Fig. i. 



Fig. 7. Blastoderm with maximum development of germ-ring. X 16. gr. 

 = germ-ring ; anf. = anterior ; per.n. = periblast nuclei. 



Fig. S. Blastoderm of later stage than PI. Ill, Fig. g. X 16. 



Fig. 9. Blastoderm of a slightly earlier stage than that of Fig. 3. 



Fig. 10. Reproduction of Dr. Clapp's figure showing " shadowy connection," 

 »(., between " germ-ring " and embryo. 



