720 OCCURRENCE AND DEVELOPMENT OF BOTIIRIOCEPHALUS LATUS. 



found a large number of smaller worms at various stages of development 

 (one to ten days old). The smallest differed from the Bothriocephali 

 of the pike used for feeding, only in the constant evagination of the 

 head, while the largest, measuring 15 cm. in length, already exhibited 

 a distinct segmentation, though no reproductive organs were recognis- 

 able to the naked eye. The size of the others varied from 2 to 8 cm. 



Not only in the dog and cat, however, but also in man, successful 

 experiments led to positive results. 



The experiments were made on three of Braun's students in 

 Dorpat, who volunteered for the purpose. None of them had ever 

 suffered from Bothriocephalus, nor did any one expel ova of Bothrio- 

 cephalus at the commencement of the experiment. In the end of 

 October, two of them (A and B) swallowed three, and one of them (C) 

 four, freshly removed Bothriocephalus larvae in milk, sausage, or bread, 

 After the lapse of a month, 30 to 40 ova of Bothriocephalus were 

 found in the first preparation made from the faeces of each, while 

 eight days previously slight intestinal pains had been felt, which 

 were due to the growing worm. The expulsion, which was brought 

 about a few days after, resulted in the case of A in two Bothrio- 

 cephali, in the case of C in three, and in the case of B in a number of 

 fragments, which probably originated from several specimens. The 

 average length of the worms was estimated at about 335 cm., the 

 average number of joints at 1209, so that the growth of the worm day 

 by day must, on an average, have resulted in a length of about 

 8 - 8 cm., representing thirty-one or thirty-two proglottides of average 

 size. Since, however, the growth takes place at the anterior end, 

 where the joints are mostly very small, the number produced daily 

 must be much greater than Braun computes. Thus it is also 

 explained how the worm, with increasing age, attains an ever greater 

 length. During their four weeks' growth the worms had liberated no 

 proglottides, as was also evident from the character of the terminal 

 joint, which had an elongated tongue-like form, instead of the more or 

 less degenerate semicircular form, which is exhibited in other cases 

 as the result of a separation of the joints which does not anatomically 

 coincide with the boundary of the segment. 



In comparing this tape-worm reared in man with that from the 

 cat, one is struck by the fact that the former has, in a shorter time, 

 grown much larger, and formed far more joints than the latter. Nor 

 is this true only of the general structure, but also of the individual 

 parts. The head of the worm from the cat is markedly smaller, the 

 anterior portion of the body extended and thin, the rest of the chain 

 narrow and lean, and composed of joints which are for the most part 

 much elongated. There cannot, however, be any doubt as to the rela- 



