A disease known as _kakke_ was a few years ago quite prevalent in Japan and other countries along the eastern coast of Asia. With the opening up of Japan to the civilized world the study of this disease by scientific methods was undertaken by the observant and intelligent natives who acquired their medical training in Europe and America. In Tokio the disease generally appears in May, reaches its greatest prevalence in August, and gradually disappears in September and October. The researches of Miura and others have fairly well demonstrated that this disease is due to the eating of fish belonging to the family of _Scombridæ_. There are other kinds of fish in Japanese waters that undoubtedly are poisonous. This is true of the _tetrodon_, of which, according to Remey, there are twelve species whose ovaries are poisonous. Dogs fed upon these organs soon suffered from salivation, vomiting, and convulsive muscular contractions. When some of the fluid obtained by rubbing the ovaries in a mortar was injected subcutaneously in dogs the symptoms were much more severe, and death resulted. Tahara states that he has isolated from the roe of the tetrodon two poisons, one of which is a crystalline base, while the other is a white, waxy body. From 1885 to 1892 inclusive, 933 cases of poisoning with this fish were reported in Tokio, with a mortality of seventy-two per cent. Fish poisoning is quite frequently observed in the West Indies, where the complex of symptoms is designated by the Spanish term _siguatera_. It is believed by the natives that the poisonous properties of the fish are due to the fact that they feed upon decomposing medusæ and corals. In certain localities it is stated that all fish caught off certain coral reefs are unfit for food. However, all statements concerning the origin and nature of the poison in these fish are mere assumptions, since no scientific work has been done. Whatever the source of the poison may be, it is quite powerful, and death not infrequently results. The symptoms are those of gastro-intestinal irritation followed by collapse. In Russia fish poisoning sometimes causes severe and widespread epidemics. The Government has offered a large reward for any one who will positively determine the cause of the fish being poisonous and suggest successful means of preventing these outbreaks. Schmidt, after studying several of these epidemics, states the following conclusions: