PARASITES OF ANIMALS. 101 



Tcenia elliptica Batsch is a similar species living in the cat, 

 and by some is thought to be the same. 



Several tape-worms of the dog have already been de 

 scribed (Tasnia echinococcus, T. coenurus, T. marginata), 

 but there is another that is equally common in some districts. 



Tcenia serrata Goeze closely resembles T. ccenurus and T. 

 marginata. The larva? live among tho viscera of rabbits and 

 hares, producing small round cysts, and the dogs get this tape- 

 worm by eating rabbits or the refuse thrown aside in dressing 

 them. The young state or larva was formerly named Cysti- 

 cercus pisiformis, in allusion to the pea-shaped cysts. 



The Broad Tape-worm of Man (Bothriocephalus latus 

 Bremser) . 



The genus Bothriocephalus differs greatly from the true 

 tape- worms (Tcenia) in many anatomical characters, but has 

 a similar form of body, divided into many flat joints. The 

 head has no suckers, but is long-oval in shape, with a long 

 and deep, groove on each side. It has no proboscis and no 

 hooks. The reproductive organs open at the middle of the 

 side of each joint, instead of the edge. 



There are numerous species living in fishes and quite a 

 number in birds. The present species grows to an enormous 

 s i ze probably larger than any other known tape-worm. It 

 grows to the length of 25 or 30 feet, and according to some 

 authors to 50 or 60 feet. It is sometimes an inch wide. The 

 joints seldom break off, either singly or in chains, but the 

 eggs are discharged by the bursting of the joints while still 

 attached within the body of the infested person. The male 

 and female organs oprn separately, the male organ being a 

 little in advance of the female orifice. The female uterine 

 organ forms a sort of rosette, with eight or ten lobes, around 

 the external orifice. 



Its fertility is remarkable, even for a tape-worm. Prof. 

 Eschricht found in one specimen 10,000 joints ; allowing each 

 of these to contain only a thousand eggs, this worm would 

 have produced 10,000,000 young. The full history of this 

 parasite is not yet known. The eggs, however, will hatch in 

 water, producing curious embryos, which are provided with 

 vibrating cilia by means of which they swim around for a 



