THE PITUITARY AND THE THYROID 



frog, and toad) have confirmed Adler's work and justify the 

 conclusion that normal metamorphosis depends as much 

 upon the anterior pituitary as upon the thyroid. The peren- 



Ht 



Fig. 43. — The effect of the destruction of the pars glandularis on the metamor- 

 phosis of the tadpole. Operated animals above, control animals below. From 

 Adler, Jrck. Entw.-mech. Organ., XXXIX (1914), -1-45. 



ni branchiate mud puppy {Necturus and Proteus) does not 

 "metamorphose" even after thyroid treatment (Jensen, 191 6; 

 Spaul, 1925; Allen, 1929). 



Adler (1914) attempted to destroy the anterior pituitary of 



[--47] 



