Tetrarhynchus erinaceus van Beneden. I. Structure of larva and adult worm

My attention was first directed to this Cestode in 1906 when I was asked to examine several specimens of edible fish which had been exposed for sale in the public markets and had been condemned as human food on account of the presence of obvious, intrusive bodies in the flesh. In three of these cases the muscles of the flesh of the fishes—a Halibut, a Megrim and a Hake—contained cysts which enclosed the larvae of a Tetrarhynchid, and on examination the latter was identified as T. erinaceus from the peculiar nature of the armature of the proboscides. In another case the wall of the stomach of a Halibut was also infected with the same larvae. Acting on an obsolete principle of Border Law the Fish Inspectors promptly condemned the fishes and then caused them to be examined. I do not think there was any valid reason for the condemnation of the articles of food, for I can find no reference in the literature to the presence of Tetrarhynchids in the human alimentary canal, and there does not appear to be any question of a possible communication of a parasite by the consumption, as food, of such infected flesh. Further the number of larvae present was far too few to lead to any emaciation of the fish, or to the likelihood of the production of toxic substances in the flesh of the animal. Nevertheless the Inspectors probably acted in the interests of the public health in condemning such articles of food as contained obvious cyst-like structures in the flesh, as to the precise nature of which they were ignorant, since there is always the possibility that these bodies might be detrimental to the health of those eating them.