IV 



THE SUPKAKENAL OEGANS 



285 



become shifted in a ventral direction round the dorsal aorta and 

 take up their position in intimate contact with the interrenal bodies, 

 lying in the posterior paired region of the interrenal on its mesial 

 face, elsewhere dorsal or lateral or even completely surrounding the 



Fig. 144. — Illustrating origin of the sclerotome as seen in transverse sections 

 through young stages of 



A, Amphioxus (for the sake of clearness the spaces have been exaggerated, and the ventral portion of 

 the diagram is taken from a rather younger stage than the dorsal) ; B, Lepidosiren, stage 24 ; C, 

 Polypterus, stage 23. ent, enteric cavity ; my, myotome ; N, notochord ; nc, nephrocoele ; jm, 

 pronephros ; s.c, spinal cord ; scl, sclerotome ; sn, subnotochordal rod ; splc, splanchnocoele. 



interrenal. The chromophile bodies stand out with great distinct- 

 ness from the interrenal by their fine grained deeply-staining proto- 

 plasm and their larger nuclei. 



We thus see that in the Amphibia the originally separate inter- 

 renal and chromophile bodies become during the course of develop- 



