108 PIGMENTARY GROWTH AFTER ABLATION OF 



morphose, their growth extends beyond the normal larval period. 

 Consequently they attain a size in excess of the normal. 



18. The sensitiveness of the hypophysectomized frog tadpole 

 to the growth-'maintaining' substance of the anterior lobe makes 

 it possible by feeding experiments to test in a particularly effica- 

 cious manner any hypophysial substance for the presence or 

 absence of this principle. 



20. Neither aqueous nor alcoholic extracts of the anterior 

 lobe of the pituitary nor the intraglandular colloid of the hy- 

 pophysis contain the growth-'maintaining' substance of this 

 gland. Conversely, the residues formed by extracting the 

 hypophysis with boiling water or boiling absolute alcohol con- 

 tain this growth substance. 



