ANNULOSA. 441 



terminal prominence. The embryo passes through a 

 similar course of development to the Trematoda; viz., 

 four forms or changes: but the embryo itself is very 

 peculiar, consisting of an oval non-ciliated mass, provided 

 upon one face with six hooks, three upon each side of the 

 middle line. The Tceniadce are found in many other 

 situations besides the alimentary canal ; the eye, the brain, 

 the muscular tissues, the liver, &c. ; the following cystic 

 worms are included in this genera, Cysticercus, Anthoce- 

 phaluSj Ccenurus, and Echinococcus. 



Von Siebold, Leuckart, and others, have shown, by many 

 interesting experiments, as feeding puppies with Cysti- 

 cercus pisiformis, that in the course of a few weeks these 

 entozoa are transformed into fully formed Tcenia serrata ; 

 again, rabbits fed with the embryo of the Tcenia^ the 

 embryo bore their way, by means of hooks, through the 

 walls of the intestine, until they reach some blood-vessel : 

 by the current of blood they are carried into the liver, 

 and here Leuckart has traced their further development. 

 These embryos grow to the 1-1 6th of an inch in length, 

 and become elongated, so as almost to resemble an Ascarid 

 in form, they then make their way to the surface of the 

 liver, and pass out into the peritoneal cavity. 



In like manner, Cysticercus fasciolaris is rapidly developed 

 within the liver of white mice ; and Cysticercus cellulosce 

 in the muscles of the pig fed with the Tcenia solium, 

 produces the diseased state of pork familiarly known as 

 " measly pork" If a lamb is the subject of the feeding 

 experiment with Tcenia serrata, the final transformation 

 will be very different ; within a fortnight, symptoms of a 

 disease known as " staggers " are manifested, and in the 

 course of a few weeks, the Cctnurus cerebralis will be found 

 transformed and developed within the brain. Von Siebold 

 pointed out the bearing of this fact upon the important 

 practical problem of the prevention of " staggers." Others 

 of the same family of parasites are quite as remarkable, 

 in giving a preference to the alimentary canal of fishes. 

 The Echinorhynchus is developed in the canal of the 

 Flounder. Tricenophorus nodulous in the liver of the 

 Salmon, attaining a more perfect development in the 

 alimentary canal of the Perch and Pike. Another, found 



