THE PARS BUCCALIS OF THE HYPOPHYSIS 43 



be able to 'utilize' the growth-maintaining ('accelerating') prin- 

 ciple of the administered anterior-lobe substance as they could 

 not do were this deficit not existent. If, then, the animals 

 suffering from such a deficit exhibited a pronounced retardation 

 in growth and if in other animals this retardation could be pre- 

 vented by pituitary administration, we would obtain a com- 

 bination of conditions giving a pronounced effect from such a 

 dietary regime. Such indeed is the case in the hypophysec- 

 tomized (albinous) frog tadpole, as has previously been pointed 

 out by the author (Smith, '18). The growth response to an- 

 terior lobe administration in such animals, as compared to the 

 normal, is greatly magnified, since, 1) the hypophysectomized 

 frog tadpole grows at a slower rate than the normal (Smith, 

 Allen) and never attains, or attains only after an extended 

 period, the size of the normal tadpole (Smith) and, 2) the oper- 

 ated tadpole supplied with bovine anterior lobe not only ex- 

 hibits a normal growth rate, but, due to the persistence of the 

 larval condition and the consequent extension of the larval 

 growth span, ultimately attains a size notably in excess of the 

 normal. By this sensitiveness of the albinous frog tadpole a 

 clear response to the growth-maintaining principle of the pituitary 

 has been secured. 26 



The ease of securing such operated material, its prolonged 

 survival after buccal hypophysectomy, and the magnified re- 

 sponse of the albinous frog tadpole to anterior-lobe adminis- 

 trations all combine to make this material of singular value in 

 testing various hypophysial extracts and residues for the pres- 

 ence or absence of the growth-maintaining ('accelerating') prin- 

 ciple. Such material alone affords an ideal way to analyze 

 physiologically the various hypophysial substances which have 

 been administered in order to determine the role of this gland 



* It will be quite evident why the term growth- 'maintaining' substance is used 

 in comparing the growth rate of the albinous larvae with the growth rate of the 

 normal. The growth rate of the albino is not accelerated by the administration 

 of anterior lobe as compared to the normal; their growth rate is maintained. Such 

 a diet, however, clearly accelerates the growth of the albinous tadpole as compared 

 to their albinous fellows on liver diet. 



