THE ACTIVE PRINCIPLES OF THE POSTERIOR LOBE OF THE PITUITARY BODY

¹ Department of Physiology of the University of Edinburgh

1. When depressor-free extracts of the posterior lobe of the pituitary body are boiled with dilute hydrochloric acid, the oxytocic, pressor, and melanophore responses evoked by them are destroyed slowly and simultaneously.

2. By treating depressor-free extracts with N-butyl alcohol, it is possible to separate a fraction into which the greater part of the oxytocic activity has passed.

3. By producing precipitates of lead sulphide in extracts by the passage of sulphuretted hydrogen gas through suitable concentrationsof lead acetate all the active principles are to some extent adsorbed. But the quantity of pressor and melanophore substance adsorbed exceeds that of oxytocic adsorbed by a significant amount.

4. With regard to the oxytocic response on the one hand and the pressor and melanophore on the other, the results show that these activities must be attributed to distinct substances.

5. The experiments provide no positive evidence that the pressor and melanophore responses are due to distinct substances.

The expenses incurred in carrying out this work have in part beendefrayed by a grant from the Carnegie Trust for the Universities of Scotland.