PLATE 10 



EXPLANATION OF FIGURES 



33 A cross-section through the largest portion of the left thyroid of a 40/5.0 

 normal frog tadpole. Liver diet. Fixed 64 days after the operative stage. X227. 



34 A cross-section through the largest portion of the left thyroid of a 40/1.5 

 albino frog tadpole. Liver diet. Fixed 64 days after epithelial hypophysectomy. 

 X227. 



35 The follicle, shown by an arrow, in figure 33. X765. 



36 The follicle, shown by an arrow, in figure 34. X765. 



132 



