Tapeworms are a group of worms the members of which live as parasites in the intestines of different vertebrates. They belong to the class or Cestoidea, in the article on which is an account of their anatomy and life-history. The typical forms belong to the family Taeniidae and the genus Taenia. The connection between the cystic and tapeworm stages was proved by experiments by Kuchenmeister in 1851, who fed cats and dogs with cysts found respectively in mice and rabbits. There are seven families of Tapeworms, of which that of the Taeniidae is the chief. Some, such as the Diphyllidae and Tetraphyllidae, are parasitic only on fish. Of the three adult forms occurring in the human subject, the Taenia solium and the Taenia medio canellata are the most common; the third form, the Bothriocephalus latus, is met with only in certain parts of Europe, and is very rarely seen in this country. The Taenia solium may attain to the length of 8 or 10 feet. The larval form of this tapeworm is known as the Cysticercus cellulosae. It inhabits the muscles of the pig, rendering the flesh "measly," as it is called, and tbe consumption of such "measly pork," in an imperfectly cooked state, is the cause of the introduction of the tapeworm into the human intestine. The larval form sometimes occurs in man, and in that event it is usually the muscles, brain, or serous membranes which are affected. The Taenia medio canellata resembles the Taenia solium in many ways. Its head is thicker, however, and it has no hooklets. The larval form of this worm occurs in the ox tribe. The presence of tapeworms in the human intestine may give rise to many symptoms of a variable and indefinite character; the diagnosis of their existence can only be certainly made by detecting their joints in the stools or by the discovery of the ova on microscopic examination. The remedy usually employed to expel the worm is the liquid extract of male-fern, a powerful drug, which should only be taken under professional advice.