i02 PIGMENTARY GROWTia AFTER ABLATION OF 



the frog, supportive evidence by the toad tadpole. Extraction 

 of this anterior-lobe substance with either boiling absolute 

 alcohol or boiling water appears not to remove this principle, 

 since the albinous tadpoles supplied with such extracts exhibit 

 the retarded growth rate typical of the liver-fed albino, while 

 those larvae supplied with the residues remaining after extrac- 

 tion grow at a normal rate. 



We have pointed out the structural modifications in the various 

 organs of the internal secretory system resulting from the early 

 ablation of the pars epithelialis of the hypophysis. By these 

 alterations eloquent testimony as to the interdependence of the 

 various widely separated members of this correlative system has 

 been secured. It will be recalled that the response of these 

 organs to the complete loss of the epithelial hjrpophysis led to a 

 diminution in their size, save in one gland, namely, the adrenal 

 medulla. It was also pointed out that the opposite response 

 is evoked by the early removal of the thyroids, the members 

 of this system undergoing an increase in size, save again the 

 adrenal medulla, which appears not to be seriously altered. It 

 is thus seen that the response of the organs of internal secretion 

 (save the adrenal medulla) to epithelial hypophysectomy is in 

 the reverse direction to that resulting from thyroidectomy, the 

 loss of the hypophysis causing a diminution, the loss of the 

 thyroid an increase in their size. 



It was further pointed out that the presence of a relatively 

 minute remnant of the epithelial pituitary waS sufficient to 

 abort the structural anomalies in these organs arising from the 

 complete loss of the epithelial hypophysis, save the case of the 

 derivatives of the infundibular process. These derivatives, of 

 which the major member is the neural lobe, are always affected 

 in any partial epithelial hs^pophysectomy. This we were inclined 

 to refer to the close anatomical relationship obtaining between 

 these two components of the pituitary. For it was shown that 



lations being merely a by-product or a refuse accumulated during the secretory 

 process. It must be admitted that such evidence is inconclusive, however, since 

 the part played by the other cells, the basophiles and chromophobes, whose cyto- 

 plasm appears to be more labile than that of the acidophiles, has not been excluded. 



