346 RAMBLES OF A NATURALIST. 



these complicated metamorphoses can only be effected 

 by the aid of certain migrations*; thus, for instance, if 

 we observe a young intestinal worm in one animal 

 species, we shall find it completely developed in some 

 other species ; generally, moreover, the first species in 

 which the intestinal worm passes the earliest period of its 

 existence is herbivorous ; and the second, or the one in 

 which it attains its definite form, is carnivorous. It is, 

 therefore, by eating herbivorous animals that the car- 

 nivora become infected with the parasites to which we 

 are now referring ; and this would appear to be a law, 

 from which even man, at least in a certain number of 

 cases, is not exempt. It is by eating raw, or badly 

 cooked pork, that a worm is swallowed in its larval 

 condition (Cysticercus), which, after reaching the di- 

 gestive canal, becomes converted into a Taenia or a 

 Bothriocephalus, parasites which have been commonly 

 confounded under the name of the tape-worm. 



NOTE XIV. 



The Mastodons were mammals resembling in all 

 respects our existing elephants, excepting that their 

 teeth were very different. Their bones have been found 



* Dr. Kiichenmeister, a physician at Zittau, was the first who 

 instituted regular experiments to demonstrate what had already 

 been suspected by several naturalists ; viz., that a Cysticercus is 

 nothing more than a young Tsenia. He clearly proved that such 

 was the case, and moreover that the state of the Cysticercus was a 

 normal, and not a teratological or abnormal state, as had been 

 supposed by several of our most distinguished helminthologists. 

 Dr. Kiichenmeister has extended his researches to the Ceenurus, 

 which has its abode in the interior of the brain of the sheep. He 

 showed that these strange worms were also the larvae, or rather the 

 nurses (Ammen) of the Tsenia, and that they in their turn were 

 produced from the matured ova of the latter. 



