III.—Poisonous Fish.
§ 626. A large number of fish possess poisonous properties; in some cases the poison is local; in others the poison is in all parts of the body.
Many fish are provided with poison glands in connection with the fins or special weapons, and such are used for purposes of defence; for example, Synanceia brachio is provided with a back fin consisting of 13 spines, each of which has two poison reservoirs; the reservoirs are connected with 10 to 12 tubular glands which secrete the poison, a clear feebly acid bluish fluid, exciting in a concentrated condition, local gangrene; in a diluted one, paralysis of the nervous centres.
Another kind of localisation is the localisation in certain of the internal organs. Remy states, that there are twelve varieties of Tetrodon in Japanese waters, all of which are poisonous. M. Minra and K. Takesaki[633] find that the poison of the Tetrodon is confined to the sexual organs of the female, and at the time of activity of these glands, the poisonous properties are most intense; but, even in winter, when the glands are atrophied, Remy found the glands were so poisonous that he could prepare from them a fluid, which, administered subcutaneously, killed dogs within two hours. The symptoms in the dog are restlessness, salivation, vomiting of slimy masses, dilatation of the pupil, paralysis and great dyspnœa. Death occurs by the lung. After death the appearances are similar to those from asphyxia; in addition to which there are small ecchymoses in the stomach and intestines; the salivary glands and pancreas are also injected. The symptoms observed in man are similar, there is headache, dilated pupils, vomiting, sometimes hæmatamesis, convulsions, paralysis, dyspnœa and death.
[633] Virchow’s Archiv, 1890, Bd. 122.
Some fishes are poisonous on account of the food they live upon; the Meletta venenosa is only poisonous when it feeds upon a certain green monad; Clupea thrissa, C. venenosa and certain species of Scarus, neither possess poison glands nor poisonous ovaries; but also derive their poisonous properties from their food. In the West Indies it is well-known that fish caught off certain coral banks are unwholesome, while the same species caught elsewhere may be eaten with safety.
A good many shell-fish, especially mussels, occasionally cause intense poisonous symptoms; those usually noticed are high fever, nettle rash, dilated pupils, and diarrhœa. It may be that in these cases a ptomaine, the product of bacterial action, has been ingested. To the agency of bacteria has been ascribed illness produced in Russia by a good many fish of the sturgeon species. The symptoms are those of cerebro-spinal paralysis. The “Icthyismus gastricus” of Germany may belong to the same type. Prochorow[634] has described illness from ingestion of Petromyzon fluviatilis in Russia. Whether the fish was eaten raw or cooked, the effect was the same, producing a violent diarrhœa, dysenteric in character. Even the broth in which the fish had been boiled produced symptoms. Fresh blood of the eel is stated to be intensely poisonous; this property is apparently due to a toxalbumin; Pennavaria[635] relates the case of a man who took, in 200 c.c. of wine, 0·64 kilo. of fresh eel blood and suffered from diarrhœa with symptoms of collapse.