THE EXPERIMENTS OF BEAUN. 719 



cavity, or quite free within the latter. Under favourable circum- 

 stances they may be kept alive as long as eight days outside their host. 

 Such were the forms which Braun experimentally demonstrated 

 to be the young stages of B. latus. He experimented first with cats 

 and dogs, in which the absence of Bothriocephalus was carefully proved 

 beforehand by examination of the faeces and the administration of 

 anthelminthics. The animals (seven cats and nine dogs) were each 

 infected with a definite number of larvae, which were mixed with the 

 carefully inspected food. The examination of the host took place at 

 various periods, after some days or some weeks. Only in two cases, 

 in a cat and in a dog, was the result thoroughly negative. In a third 

 case of a cat, which in consequence of repeated treatment with 

 kamala and castor oil, was affected with enteritis, there was found in 

 the thick intestinal mucus a single Bothriocephalus, little modified, but 

 still living, though with the posterior end somewhat lacerated. In all 

 the other cases, however, tape- worms were found, in numbers varying 



FIG. 379. Young Bothriocephali FIG. 380. Head of a Bothrio- 



from the intestine of the cat, after cephalus reared in the cat from 



feeding with bladder-worms from bladder-worms from the pike, after 



the pike (nat. size). Braun. (x36.) 



with the abundance of the feeding, and at degrees of development 

 corresponding to the periods which had elapsed since infection. A 

 dog which was still sucking, and which had been fed with seventeen 

 bladder-worms, exhibited, ten days later, fifteen tape-worms, which, 

 in spite of the absence of reproductive organs and their small size 

 (from 9 to 14 cm. in length), were undeniably specimens of B. latus. 

 In another case, in which the animal (a cat), after an interval of six 

 or seven weeks, was again fed with flesh of the pike and burbot 

 till the examination ten days afterwards, three Bothriocephali were 

 found in the gut, half a metre long and six or seven weeks old, with 

 at least 400 joints, of which the last exhibited almost mature repro- 

 ductive organs and eggs within the uterus ; but besides these were 



