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p. E. SMITH 



oral ectoderm. The hypophysis can now be easily distinguished 

 from the entoderm. Just dorsal to the hypophysis is a well 

 marked infundibular recess, which is more prominent at this 

 stage than at any other. The walls of the infundibulum have 

 become much thinned. 



Fig. 7 A medial sagittal section through the infundibular region of a larva of 

 Stage VIII. X 125. 



Fig. 8 A medial sagittal section of same region. Larva of a later Stage VIII. 

 X 125. 



REFERENCES 



arch., archenteron hyp., hypophysis 



ch., optic chiasma pr. en., pre-oral entoderm 



ec. n., nervous layer ectoderm (stratum s., space formed by the cephalic growth 



basale) of embryo 



ec. 0., outer layer of ectoderm t. p., tuberculum posterius 



Stage XI (fig. 39) shows but little advance in the growth of the 

 hypophysis. There has been an ingrowth of mesoderm between 

 the anterior commissure and the optic chiasma. 



In later stages the strand connecting the hypophysis and oral 

 ectoderm is lost. It is difficult to determine the fate of the cells 

 composing this strand. I was not able to distinguish them from 

 the surrounding mesenchymal cells. I believe the hypophysis in 



