THE PARS BUCCAL1S OF THE HYPOPHYSIS 101 



of the albino in endocrine extracts, the specific endocrine de- 

 ficiency would appear to be disclosed. In this we have been 

 greatly aided by the different endocrine pictures obtaining in 

 completely and partially hypophysectomized larvae, for it will 

 be recalled that both of these types of animals exhibit a pig- 

 mentary fault. Since all the endocrine glands save the pituitary 

 are of normal structure in the partially hypophysectomized (but 

 albinous) larvae, it would appear that neither the adrenal com- 

 ponents, the epithelial bodies, nor the thyroid are at fault. 

 The thyroid can further be freed from participation in this 

 disturbance since the pigmentary system of the thyroidectomized 

 tadpole is normal. Further, it will be recalled that the feeding 

 of posterior-lobe tissue (including the pars intermedia), alone, 

 of all the administered glandular substances (thyroid, adrenal 

 cortex, adrenal medulla, and anterior lobe), effected a partial 

 replacement of the epidermal melanin, although, curiously, at 

 the same time, increasing the abnormal contraction of the epi- 

 dermal melanophores. It was further shown that the immersion 

 of these larvae in pars intermedia emulsion alone of the internal 

 secretory extracts produced a normal functional state in the 

 chromatophore system. Thus, the evidence derived from these 

 three lines of investigation all points to a fault in the posterior- 

 intermediate lobe secretory mechanism as being responsible for 

 the pigmentary disturbance obtaining in the larvae suffering 

 from either a partial or total loss of their epithelial hypophysis. 

 The alimentary assimilation of the fresh glandular lobe of 

 the pituitary has supplied the growth-maintaining principle to 

 the animals exhibiting a retarded growth rate induced by buccal 

 hypophysectomy. 46 Unequivocal proof of this is furnished by 



46 What element of this structurally diverse gland contributes this growth prin- 

 ciple is obscure. Histological examination of frozen sections (15 to 20 [L) reveals 

 that extraction with boiling absolute alcohol does not appreciably diminish either 

 the number or size of the most characteristic element of this gland, the acidophilic 

 granulations. Evidence determinative of the dissolving action of boiling distilled 

 water is more uncertain because of the macerating action upon the connective 

 tissues and the consequent difficulty in the examination of this material. Yet it is 

 certain that a considerable number of these granules survive such treatment. That 

 the tissue thus extracted exhibits the characteristic growth effects of the fresh gland, 

 while the extracts do not exhibit such effects, supplies evidence against these granu- 



