FIG. 95. Stages in the embryology of the earthworm. A, two-celled stage ; 

 B, four-celled stage ; C, six-celled stage ; D, eight-celled stage ; E, bias- 

 tula in section; F, blastula flattened; G, stage showing mesoblastic 

 bands ; H, gastrula ; J, older gastrula ; K, longitudinal section of later 

 stage, bl., blastoccel ; bp., blastopore ; ec., ectoderm ; en., entoderm ; 

 mac., macromere ; mes., mesoderm ; mic., micromere ; mm., mesomeres. 

 (From Bourne after Wilson.) 



