PLATE 5 



EXPLAXATIOX OF FIGURES 



R. sylvatica. Hypophysis. Representative specimens. Abbreviations: A., 

 anterior, S., superior, and /., inferior lobes of hypophysis; E., eosinophilic cells 

 of inferior lobe; In., infundibulum. Median sagittal sections. 



56 Normal half-grown larva (same as fig. 21). X 65. 



57 Full-grown normal larva before metamorphosis. X 65. 



58 Thyroidless larva of same age as that of figure 57, but slightly larger. 

 Shows hyperplasia. X 65. 



59 Young frog. X 65. 



60 Young frog. Comparison with figure 59 shows variation in size of hy- 

 pophysis. X 65. 



61 Cells from the three lobes shown in figure 57. X 670. 



62 Cells from figure 58. X 670. 



63 Large thyroidless larva five months older than larva of figure 58. X 65. 



60 



