THE PITUITARY BODY 



tectomy than after both pancreatectomy and hypophysec- 

 tomy. Hypophysectomy alone was without effect on the 

 blood- sugar concentration. Matthews (1933) observed that 

 the adaptation of Fimdulus to colored backgrounds, finally 

 effected by changes in the chromatophores, was not altered 

 by hypophysectomy. 



The ejects of hypophysectomy in amphibia. — In amphi- 

 bian larvae (salamander, newt, frog, and toad), the most 

 striking single effect of hypophysectomy is the failure of the 

 animals to undergo metamorphosis. Adler (1914) performed 

 the first experiments in tadpoles {Rana temporaria) in which 

 he attempted to destroy the pars glandularis by means of a 

 galvano-cautery. The mortality among the operated tad- 

 poles was enormous. Ten of the surviving animals did not 

 undergo metamorphosis. In some of these no cells of the 

 pars glandularis could be found histologically; there was also 

 an associated atrophy of the thyroid and the gonads. Other 

 experiments of Smith (1916 and later) and Allen (1917 and 

 later) were performed in very young tadpoles from which it 

 was possible to remove the whole buccal anlage without in- 

 jury of the mouth. Some of the operated and normal animals 

 of Adler and Smith are shown in Figures 43 and 45. In addi- 

 tion to failure to undergo metamorphosis, due to a hypofunc- 

 tion of the thyroid (see chap, vii), a retardation in growth, an 

 atrophy of the adrenal cortex and of the epithelial bodies 

 (homologous with the mammalian parathyroids), a persistent 

 fat-organ, and a change in pigmentation (albinism) follow the 

 extirpation of the pars buccalis in tadpoles. 



Tadpoles {R. boylei) continue to grow for about two months 

 after the removal of the pars buccalis. Their rate of growth is 

 about the same as that of normal animals until the time of the 

 normal mid-larval period subsequent to which it becomes 

 markedly reduced (Smith, 1916, 1918, 1920). Similarly, tad- 

 poles of R. aurora draytoni grow much more slowly after the 

 excision of the pars buccalis than do normal or thyroidecto- 



[36] 



