(_a_) The harmful effects are not due to putrefactive processes. (_b_) Fish poisoning in Russia is always due to the eating of some member of the sturgeon tribe. (_c_) The ill effects are not due to the method of catching the fish, the use of salt, or to imperfections in the methods of preservation. (_d_) The deleterious substance is not uniformly distributed through the fish, but is confined to certain parts. (_e_) The poisonous portions are not distinguishable from the nonpoisonous, either macroscopically or microscopically. (_f_) When the fish is cooked it may be eaten without harm. (_g_) The poison is an animal alkaloid produced most probably by bacteria that cause an infectious disease in the fish during life. The conclusion reached by Schmidt is confirmed by the researches of Madame Sieber, who found a poisonous bacillus in fish which had caused an epidemic. In the United States fish poisoning is most frequently due to decomposition in canned fish. The most prominent symptoms are nausea, vomiting, and purging. Sometimes there is a scarlatinous rash, which may cover the whole body. The writer has studied two outbreaks of this kind of fish poisoning. In both instances canned salmon was the cause of the trouble. Although a discussion of the treatment of food poisoning is foreign to this paper, the writer must call attention to the danger in the administration of opiates in cases of poisoning with canned fish. Vomiting and purging are efforts on the part of Nature to remove the poison, and should be assisted by the stomach tube and by irrigation of the colon. In one of the cases seen by the writer large doses of morphine had been administered in order to check the vomiting and purging and to relieve the pain; in this case death resulted. The danger of arresting the elimination of the poison in all cases of food poisoning can not be too emphatically condemned.