ABSTRACT
Qualitative and quantitative studies of the active substance in the anterior lobe of the pituitary gland stimulating amphibian metamorphosis have suffered considerable restriction on account of the limitations of the animal test, in which the specific response—the production or acceleration of metamorphosis— is confined to a small range, and the lack of information upon its chemical nature and relationships (Spaul, 1930). Attempts have been made in recent work to overcome these difficulties by seeking for an interpretation of this biological activity in chemical terms, and so establish a chemical test having wider application. Little progress has been made so far, but a correlation of the biological activity with chemical methods, providing also a means of studying chemically the activity itself, has been discovered (Spaul and Myddleton, 1930).
