66 



PIGMENTARY GROWTH AFTER ABLATION OF 



effect has been produced in normal larvae by such alimentary 

 regimes. 



One article of diet, liver — the chief nutritive substance sup- 

 plied — is common to the specimens of the second division. 

 That the retardation in the growth rate of these specimens is 

 not due to a growth-retarding substance in the liver, but to the 

 absence of the hypophysial growth-maintaining substance, is 

 clearly indicated by three lines of evidence: 1) we should have 



TABLE 5 



Table giving the number of normal, thyroidectomized, and albinous toad larvae on which 



the accompanying growth-curves are based 



■ Killed accidentally. 



to likewise assume that such growth-retarding substances were 

 in adrenal cortex, adrenal medulla, and posterior lobe, for the 

 same growth delay exists when albinous larvae are fed with 

 any of these substances; 2) Mendel and Osborne ('18) have shown 

 that the proteins of liver are adequate for the needs of nutrition 

 in mammalian growth; 3) normal frog larvae supplied with a liver 

 diet exhibit an entirely normal rate of growth. 



It seems clear, then, that the normal growth rate of the al- 

 binous specimens receiving fresh anterior lobe or its residues is 

 due to an ahmentary replacement of the growth-maintaining 



