PROGRESS OF VETERINARY SCIENCE AND ART. 527 
blance by Yon Siebold, in 1844, which afterwards led to the 
researches respecting the specific identity of the hydatid and 
tape-worms. Dr. Allen Thomson says, “ Dr. Henry Nelson 
made the same observation without a knowledge of Von 
Siebold’s views, and I repeated them with the same result ; 
and Dr. Nelson came to the same conclusion, now generally 
regarded as established, that the cat receives its taenia crassi - 
collis along with the flesh of the mouse or rat of which it has 
made prey.” 
The Cercariae, opalescent infusorial animalcules, were first 
studied by Muller, then by Nitzch; and, lastly, Bojanus, in 
1818, recognised them as parasitic in certain snails, enclosed 
in living bags, or sporocysts , which were then called the 
“ yellow worms of Bojanus.” Von Baer, in 1826, showed 
the relation between the Cercariae and their sporocysts. 
M. Wagner and Von Siebold also contributed to advance 
our knowledge respecting them ; and, lastly, Steenstrup dis- 
covered the changes the Cercariae underwent to become true 
flukes. Ehrenberg, in 1 852, disputed Steenstrup’s accepted 
metamorphoses, and only gives the resemblance of the tailless 
Cercariae with a trematode worm. 
From the near relationship between the sucking and tape- 
worms, it was rendered probable that even these passed 
through different forms in their development, and that the 
hydatids were to be looked upon as transitionary forms of 
the taenia. 
Van Beneden sought, from 1849, to bring to bear his views 
that the species of Tetrarhyncus constituted the larvae of the 
Bothriocephalus.* Von Siebold, on the contrary, thought 
the Cysticerci were diseased tapeworms ; diseased because 
growing in situations ill suited for their development. 
Dr. Kuchenmeister, of Zittau, instituted certain very able 
experiments to settle this question. He made dogs and cats 
swallow hydatids which developed into tapeworms in their 
intestines. From the hydatids of livers of mice arose the 
taenia crassicollis in the intestine of the cat, and from the 
cysticercus of the hare or rabbit, the taenia serrata fn the 
intestine of the dog ; so that, the bladder of the hydatid is 
lost, the head of the worm attaches itself to the mucous 
membrane, and the rings constituting the body of the tape- 
worms, and including the organ of reproduction, are formed. 
These interesting experiments were repeated by several 
other zoologists (also with caenuri and echinococci) and 
confirmed. 
* Bremser thought the Tetrarhyncus the young of the Anthocephalus or 
Ithyncobothrius. 
