HELMINTHES. 45 



outside of the kyst, the animals being restricted to its iuside. It occurs in 

 the liver, spleen, and other parts, and is not exclusively confined to man. 



1). Cestoidea. 



Cysticercus is found in man as well as in animals, between the tissues of 

 the muscles, sometimes penetrating to the eye-ball, the heart, and the brain. 

 The form is that of the Cystica (with which it is usually and perhaps cor- 

 rectly placed), whilst in some other respects it approaches the Cestoidea. 



What is called " measles" in hogs arises from an abundance of enkysted 

 worms {Cysticercus cellulosm^ jpl. 11^ jig. 30), which have been fuund occu- 

 pying as much space as the brain in these animals, and causing convulsions 

 and death. 



The intestinal worms of the genus Ligula (Z. ciiigulum^ ]^. 77, jig. 34) 

 are flat, ribbon-shaped, without articulations, marked with a longitudinal 

 stria, and also transversely striate. They live in birds, and especially in 

 fishes. The species figured is from one to five feet long, and is found in the 

 Cyprinus hrania of Europe. This worm is said to be eaten in some parts 

 of Italy. Botlirimonus sturionis infests the American Acf'jyeiiser (Kcyrliyn- 

 chus. It is not articulated, it has a longitudinal impressed line above and 

 below, with numerous raised points along it, those beneath having a pore. 

 The head is sub-globular, with a double sucker. 



The genus Bothriocej^halus (named from IjotJiws., a groove, and kephale, 

 the head) is a long, flat, jointed worm, with a longitudinal groove upon each 

 side of the sub-quadrate head, distinguishing it from Tcenia^ or the true 

 tape-worm. It is also distinguished by having the segments much wider 

 than long, and the openings from the ovaries are beneath, and not lateral. 

 The genus infests birds, fishes, and reptiles ; and one species, B. latus 

 (j)l. 77, jig. 32), infests man in Eussia, Switzerland, and some other parts 

 of Europe. 



The common tape-worm, Tcenia solium {pi. 77., jig. 33), is composed of 

 flat, sub-quadrate articulations, which are very small and fragile for some 

 distance from the head, so much so that this part is rarely obtained perfect, 

 and the small head was for a long period unknown. The head is globular 

 and provided with four terminal suckers, arranged in a square around the 

 mouth. The alimentary canal is double, being composed of an intestine 

 nmning along each side of the body, with a transverse canal connecting 

 the opposite sides at the beginning of each segment, giving the interstices 

 the appearance of a ladder. The centre of each segment is occupied by 

 distinct generative organs of both sexes, which have their outlet in a lateral 

 pore, alternately upon the right and left side of the segments. As each 

 segment is capable of producing a large number of eggs, it is difiicult to 

 conceive why the animals should be comparatively so few in number. 

 This species attains a length of twenty feet or more, and a single one is 

 usually confined to a single individual, although as many as twenty have 

 been found together. Tcenia cateniformis {jig. 31) is about an inch long, 

 and infests the cat. 



11. Parenchymata. 



These are soft contractile bodies, without any appearance of division 



249 



