in OCCURRENCE OF CESTODES 8 I 



able alternation of asexual generations in the larval state, with 

 a sexual adult stage. ' 



Bothriocephalus lotus Brems., the broad tape-worm, which 

 attains a length of 20-30 feet, or even more, occurs in man 

 endemically in the eastern Baltic provinces, certain parts of 

 Switzerland, generally throughout Bussia (especially near Kasan), 

 in North America, and commonly in Japan, that is, in districts 

 where the population partake largely of pike or other fish in a 

 raw or partially-cooked state. Elsewhere it occurs sporadically, 

 and in Munich, where it was unknown before 1880, its presence 

 has been traced to emigrants from infected districts, who settled 

 on the shores of the Starenberger Lake, from which Munich was 

 supplied with fish. How the pike, the usual but not invariable 

 intermediate host, becomes infested (and its musculature is 

 frequently riddled with the larvae) we do not accurately know, 

 but some Invertebrate, the prey of the pike, is probably the first 

 host into which the free-swimming ciliated larva (Fig. 42) finds 

 its way. In Greenland, B. cordatus is very common in the dog, 

 and probably also in man, though few cases have been recorded. 

 B. mansoni Cobb. ( = B. liguloides Leuck.) was, till recently, 

 known only in the larval state from China and Japan. Iijima, 

 however, has found older specimens in the latter country. B. 

 cristatus Dav. is a species founded somewhat doubtfully on two 

 fragments found, one in a child, the other in a man, in France. 



Occurrence of Cestodes in Domestic Animals. 1 Among 

 domestic animals, the dog is, undoubtedly, the most frequently 

 attacked by Taeniae. Six species of Taenia (T. serrata, mar- 

 ginata, coenurus, echinoccccus, krabbei, and possibly T. serialis), 

 Dipylidium caninum (the commonest form), Mesocestoides lineatus, 

 and three or four species of Bothriocephalus' have been found in 

 the dog. The table of life-histories (p. 83) shows that sheep, 

 rabbits and other Bodents serve as the intermediate hosts, in 

 which the cystic stages of the species of Taenia are found. 

 Hence the prevalence of T. serrata in a given locality is con- 

 nected with the abundance there of the rabbit and hare, in which 

 the larva (Cysticercus pisiformis) occurs. Bothriocephalus cord" f us 

 develops from the young stage present in the fish which the 

 Icelanders give to their dogs. In Iceland and certain parts of 



1 The distinctive features of these and the foregoing tape-worms are given on 

 pp. 89-90. 



VOL. II G 



