Cholinergic Substance in the Caudal Neurosecretory Storage Organ of Fish

Abstract
Cholinergic substance exists in homogenates of caudal neurosecretory storage organs of fish. The caudal organs of fresh-water fish contain about 10 times the amount found in caudal organs of marine fish. The substance in the caudal organ of the carp is more than 100 times as concentrated as that in the brain.