52 PIGMENTARY GROWTH AFTER ABLATION OF 



invariably exhibited by albinos supplied with this diet. Follow- 

 ing the substitution of a hypophysial for a liver diet, a normal 

 growth rate is exhibited for a time, the albinos, however, not 

 attaining the large size induced by continuous anterior-lobe 

 feeding (tig. 1). 



It seems clear from these three groups that neither an inter- 

 rupted diet of anterior-lobe substance nor a full diet of this 

 substance during merely the early or the late portions of the 

 growing period will bring about a normal growth of the albinous 

 larvae. It is indeed remarkable that albinous larvae, growing 

 at a normal rate in response to anterior-lobe administration, 

 will exhibit a growth retardation so quickly on the withdrawal 

 of this 'substitution' diet. 



It may then be regarded as demonstrated that the retarda- 

 tion in growth, resulting from the early removal of the epithelial 

 hypophysis, can be ameliorated by a continuous diet of bovine 

 anterior lobe, the growth curves of the albinous larvae thus 

 treated showing no deviation from normality save by its con- 

 tinuance beyond the normal growing period. It will likewise be 

 granted by the reader that such material is of peculiar value for de- 

 termining the presence of the growth-maintaining principle in any 

 hypophysial extractive or its residue. The experimental utiliza- 

 tion of this material should show us whether the extraction of the 

 fresh anterior lobe with boiling alcohol or boiling water removes 

 or destroys this growth-maintaining principle — a test which can 

 be provided with a double check, since both the extract and its 

 residue can be fed to similar groups of albinos. To the group of 

 four substances (aqueous extract and its residue, alcoholic ex- 

 tract and its residue) which were submitted to this test was 

 added the hypophysial colloid occurring in the intragiandular 

 (vestigial cleft) of this gland. 30 



10 In the preparation of the aqueous extract and its residue, the ground fresh 

 anterior-lobe substance was extracted in a modified Bailey-Walker apparatus (Rob- 

 ertson) over boiling aq. dest. for forty-eight hours, five bovine anterior lobes being 

 placed in each alunduin thimble. After this prolonged extraction the substance 

 was dried, powdered, and placed in vials tightly corked. Each group of specimens 

 20 to 24) received the dried residue from one and a half glands at a feeding. The 

 clear, yellowish extract on evaporation yielded a dark, readily soluble amorphous 



