STUDIES ON THE PITUITARY MELANOPHORE-EXPANDING HORMONE WITH REFERENCE TO ITS IDENTITY WITH ACTH

Abstract

SUMMARY: 1. The standard Xenopus method for the assay of pituitary melanophore-expanding hormone has been critically examined, and the results from various assay procedures are statistically analysed. 2. Log dose-response data are well fitted by a linear regression curve. Responses at 3 hr give a steeper curve than those at 1½ hr. 3. Results collected 6 months apart show that the mean and slope of dose-response curves remain constant when Xenopus are given regular dosage; there is, however, a progressive increase of variance with time shown by the colony under these experimental conditions. 4. Evidence is presented to show that Xenopus must be minimally disturbed during assay, and that assay doses must be given not less than 1 day apart.