Abstract
Summary
The frog is a satisfactory animal for the assay of gallbladder contracting materials and has the advantage over others of time and expense. Assays on normal summer frogs give lower figures than at other seasons. There is no significant variation in the assays on spring, early summer, male and female frogs, or winter frogs. Starved frogs have gallbladders greatly distended with thick bile. Such distended bladders do not respond well to S.I. The response of the frog's gallbladder to S.I. is not due to the presence of histamine or choline-like substances in the extracts. A modification of Ivy's method for the preparation of S.I. has resulted in the isolation of a more potent preparation and the recovery of much active material lost by the original procedure.
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