ORIGIN OF PARASITES 15 



developed piece of tapeworm situated between the caudal vesicle and 

 the cysticercus head. 



Guided by correct views, F. Kuchenmeister undertook in Zittau 

 the task of confirming the metamorphosis of Cysticercus pisiformis 

 of hares and rabbits, into tapeworms in the intestine of the dog 

 by means of feeding experiments. The first reports on the subject, 

 published in 1851, were not likely to meet with universal approval, 

 because Kuchenmeister first diagnosed the actual tapeworm he had 

 been rearing as Tcenia cmssiceps, afterwards as Tcenia serrata, and 

 finally as Tcenia pisiformis n. sp. However, in any case, Kuchenmeister, 

 by means of the reintroduction of experimental investigation, rendered 

 a great service to helminthology. 



The publication of Kiichenmeister's works induced v. Siebold 

 to undertake similar experiments (1852 and 1853), which were 

 partly published by his pupil Lewald in 1852. But the positive 

 results obtained hardly changed Siebold's opinion, for although he 

 no longer considered the bladder-worms as hydropically degenerated 

 tapeworms, he still regarded them as taeniae that had strayed. The 

 change of opinion was partly due to an important work of the 

 Prague zoologist, v. Stein (1853). He was able to examine the 

 development of a small bladder-worm in the larvae of the well-known 

 meal-worm (Tenebrio molitor] and to demonstrate that, as Goeze had 

 already proved in the case of Cysticercus fasciolaris of mice, first the 

 caudal vesicle is formed and then the scolex, whereas Siebold believed 

 that in bladder-worms the posterior end of the scolex was formed 

 first, and that this posterior end underwent a secondary hydropic 

 degeneration. 



In opposition to v. Siebold, Kuchenmeister successfully proved 

 the necessity of the bladder- worm stage by rearing tapeworms 

 in dogs from the Cysticercus tenuicollis of domestic mammals and 

 from the Ccenurus cerebralis of sheep. He, and simultaneously 

 several other investigators independently, succeeded, with material 

 provided by Kuchenmeister, in rearing the Ccenurus cerebralis in 

 sheep from the oncospheres of the Tcenia ccenurns of the dog (1854). 

 R. Leuckart obtained similar results in mice by feeding them with the 

 mature proglottides of the Tcenia crassicollis of cats (1854). 



Kuchenmeister also repeatedly reared the Tcenia solium of man 

 from the Cysticercus celluloses of pigs (1855), arid from the embryos 

 of this parasite P. ]. van Beneden succeeded in obtaining the same 

 Cysticercus in the pig (1854). As Kuchenmeister distinguished the 

 Tcenia mediocanellata, known to Goeze as Tcenia saginata, amongst 

 the large taeniae of man (1851), so it was not long before R. Leuckart 

 {1862) succeeded in rearing the cysticercus of the hookless tapeworm 

 in the ox. It is particularly to this last-named investigator that 

 helminthology is indebted more than to any other author. He 



