THE PITUITARY AND THE THYROID 



croscopic evidence of hypofunction. Smith's monograph 

 (1920) gives a detailed account of all the anatomical changes 

 resulting from hypophysectomy in the tadpole. In Figure 45 

 the albinism and persistence of the larval form in the hypo- 

 physectomized as compared with the normal tadpole are 

 illustrated. 



Similar findings in urodele amphibia were reported by 

 Schotte in 1926 {Triturus cristatus^ T. alpestris^ and Salaman- 



FiG. 45. — Albinism and lack of metamorphosis as a result of hypophysectomy. 

 Control animal above; operated animal below. From Smith (1920). 



dra maculosa) who could prevent metamorphosis if he per- 

 formed hypophysectomy sufficiently early. Adams and her 

 co-workers (1930, 1933) showed that hypophysectomy in 

 T. viridescens and T. cristatus prevented molting and that 

 this effect was the result of an inactivity of the thyroid. Ex- 

 tracts of the mammalian pituitary stimulate the thyroid and 

 cause molting (which is excessive in normal animals) in either 

 the normal or the hypophysectomized salamander, T. viri- 

 descens (Adams, 1934). Implants of the fowl pituitary also 

 cause histological signs of stimulation of the thyroid (Stein, 

 1934). For a discussion of numerous observations on the ef- 



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