The relation between the common bladder-worm of the pig, or cysticercus cellulosæ, and the hook-bearing tapeworm that infests the intestines of man, known as tenia solium, was not recognized until 1853, when Küchenmeister first called attention to the resemblance of the bladder-worm head and the head of tenia solium.1 His observations were soon corroborated, mainly on experimental grounds, by Leuckart,2 Haubner, Van Beneden and many others3—that the eggs of tenia solium, when introduced into the stomach of the pig, by feeding pigs with ripe segments, develop into the familiar bladder-worm (measly pork)—and that the latter is the larval form of the above tenia. Furthermore, the life cycle of this parasite is completed by the metamorphosis of the bladder-worm into the adult tapeworm, when the bladder-worm is taken into the stomach of man and in a few of the lower animals. The knowledge of its life history