THE EARTHWORM 



41 



7n.es. 



Fig. 9 



A. Lateral view of an embryo oi Lutnbricus fmtidus^ in which the germ bands are 

 clearly visible. B. Ventral view of the same embryo. C. Lateral view of an older 

 embryo. D. Transverse section through the ventral half of an embryo, showing 

 the cleavage of the mesoblaj^t. E. Early stage in the development of a nephridlum 

 of Rhynchebnis^ showing the pronephridiostome with a single flagellum. F. A 

 later stage in the development of a nephridium. G. Nephridium in the eleventh 

 somite of a young worm. //. View of an older embryo of Lunibriczcs. ec, ecto- 

 derm ; en, endoderm ; ent, enteron ; ejct, external pore of nephridium; go, 

 gonad ; nies, mesoderm ; tftvi, mesomeres ; nep, nephroblasts ; neur, neuro- 

 blasts ; ftph, nephridia ; pnp, pronephrostome ; s.s, septa; j/, stomodgeum. {A ' 

 to D after E. B. Wilson ', E to G after Vejdovsky ; H after Kowalevsky.) 



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