VIII.—On a Tetracotyle (T. phoxini) in the Brain of the Minnow

Abstract

During the course of experiments on the toxic effects of tetrachlorethane on minnows, Phoxinus phoxinus (L.), Mr J. Wilson Dougal, B.SC., found “cellular bodies” in a portion of the brain tissue of a dead minnow which he had spread on a microscopic slide. Sections of the head of the minnow were subsequently made by Mr Richard Muir and submitted to me for an opinion on the nature of the bodies. Examination showed that they were immature Trematodes of the family Holostomidæ. I handed the sections and a living minnow, sent at the same time (May 1923), to Miss Bannerman for further study, remarking that the only Trematode hitherto recorded as occurring in the brain of fresh-water fish in Britain was a Tetracotyle in the brain of the lamprey and the ammocœte. I subsequently directed her attention to Mataré's account (1910) of a similar worm which had been found in the brain of minnows collected in Switzerland and in Germany. Miss Bannerman studied numerous examples of the parasite during June and July 1923 and in September 1925, but she had to leave in October 1925, before the work could be completed, to take up a post in India. The comparison with previously recorded species of Tetracotyle, the discussion on the morphology of the ventral sucker, the account of the excretory canals, and a number of details in other parts have been added since she left.—J. H. A.