72 PIGMENTARY GROWTH AFTER ABLATION Of 



% 



surface (figs. 26, 29). This lobe is thus profoundly modified by 

 the loss of its associate. It attains normal development neither 

 as regards size, form, nor position. 38 In its response to buccal 

 hypophys.ectomy the reduction of this gland thus aligns it with 

 the thyroid and the adrenal cortex reduction. Indeed, in those 

 animals suffering only a partial loss of the epithelial hypophysis, 

 the thyroid and adrenal glands are usually not altered in develop- 

 ment, but the neural hypophysis is invariably atypical. 



In an earlier section of the paper we have referred to the 

 type of tadpole in which the removal of the epithelial hypophysis 

 was incomplete. Since these animals usually manifest definite 

 pigmentary alterations, we have designated them 'partial al- 

 binos.' 39 Especial interest attaches to the examination of the 

 endocrine system, more particularly its hypophysial components 

 in this type, since we have here an intermediate condition be- 

 tween a complete deficiency of the epithelial hypophysis and 

 a normal structure. A study of this form throws much addi- 

 tional light upon the interesting relationship obtaining between 

 the neural and epithelial components of the pituitary as well as 

 supplying evidence bearing upon the endocrine locus responsible 

 for the pigmentary deficiency. 



In the partial albinos no uniformity in shape is displayed by 

 the vestige of the epithelial hypophysis. It is usually oval in 

 outline and of a variable thickness (figs. 27, 30). Only occa- 

 sionally do we find it displaying the normal division into glandu- 



38 The findings of Allen (Abstracts, Am. Assoc. Anatomists, 1917) are distinctly 

 at variance with those reported here. This author states, "The pars nervosa of 

 the hypophysis forms normally in tadpoles, both Rana and Bufo, from which the 

 anlage of the anterior lobe has been removed." As I have previously pointed out, 

 a median sagittal section of the infundibulum usually shows a neural hypophysis 

 of normal or even enlarged proportions. By modeling this component, unmis- 

 takable evidence concerning its diminution in size and atypical form is secured, 

 however. 



39 1 called attention in 1916 (Proc. Am. Assoc. Anat.) to an albinous tadpole in 

 which a leg development took place. At that time the minute buccal fragment 

 displayed by this animal had not been noted. Allen, in 1918, called attention to 

 the complete metamorphosis of certain toad and frog tadpoles with an imperfect 

 hypophysis and displaying a definite pigmentary deficiency. 



