40 PICMKXTARY GROWTH AFTER ABLATION OF 



thus appear from these responses that the extracts or diets of 

 the intermediate and posterior lobes of the pituitary were inti- 

 mately concerned in this pigmentary fault. Corroborative evi- 

 dence is supplied by a study of the structural malformations 

 occurring in the endocrine glands of the albinous and the par- 

 tially hypophysectomized larvae. For, as will be detailed in a 

 subsequent section (4), the' neural hypophysis, thyroid, epi- 

 thelial bodies, adrenal cortex, and adrenal medulla suffer definite 

 and often profound structural and size alterations in the albino. 

 In the partially hypophysectomized tadpole, however, whose 

 pigment system may suffer a profound disturbance (indeed, the 

 picture of albinism approaching that of the true albino), none 

 of these internal secretory organs save the posterior lobe and 

 the associated pars intermedia exhibit significant structural 

 defects. 24 The evidence thus points to a deficiency in the secre- 

 tion formed by either the posterior or intermediate lobes of the 

 pituitary or by the 'interaction' of these two intimately asso- 

 ciated components of the pituitary as being responsible for the 

 pigmentary upset in the larvae. 25 



24 Further evidence freeing the thyroid from responsibility for this pigmentary 

 disturbance comes from the thyroidectomized specimens whose pigmentary system 

 is not at fault. 



25 Indeed, the pigmentary system in the frog, at least, appears to be very sensitive 

 to hypophysial disturbance. This is shown in a striking way by one specimen of 

 a considerable number (seventy) of tadpoles which suffered the extirpation of their 

 pineal glands in an early larval stage. In this operation the aqueduct of Sylvius 

 of one specimen was inadvertently injured, an injury leading to its complete occlu- 

 sion. This apparently induced an internal hydrocephalus of the III and lateral ven- 

 tricles with the consequent inevitable pressure upon the pituitary, sections revealing 

 a flattened gland slightly reduced in size. The specimen exhibited unmistakable 

 albinism, a condition unquestionably referable to the compression of the pituitary 

 gland, since it is certain that this pigmentary disturbance was not due to the loss 

 of the pineal body, for, as has been shown by Laurens ('13), the loss of this gland 

 produces no fault in the pigmentary system, ample confirmation of which has been 

 made in tin's laboratory. 



