12 



and he even saw what he calls colourless or oviform granulations, in 

 those taken from the human subject, and which he supposed a mode 

 of reproduction of the cyst — which he considered to be animated, 

 and of which he constitued a distinct genus under the name of 

 Acephalocyst. Rudolphi opposed this opinion of Laennec, and in 

 1808 again divided the class of vesicular worms into four genera: 

 1. Cysticercus. 2. Anthocephalus. 3. Canurus. 4. Echinococcw, 

 under which he included those worms which were collected in large 

 numbers in a common cyst, without, however, adhering to it in 

 any way. 



He subdivided the genus into three species, but has been unable 

 to point out any distinctive characters between them. 



After this, MM. Desmarest and H. Cloquet committed the extra- 

 ordinary error of confounding the cyst itself with the animalcule, an 

 error participated in also by Bremser, in 1817, although he mentions 

 the contained animalcules ; of which, however, he appears to have had 

 a very obscure notion. He, however, recognized their animal nature 

 in the globular corpuscles taken from cysts found below the clavicle 

 of a woman. 



Numerous other writers have more or less accurately treated on the 

 same subject, but I will only farther advert to the researches of 

 Kuhn, and to his opinions, which have so much modified the views 

 of naturalists since his work appeared in 1832. 



He adopted the erroneous opinion of Laennec, as to the reproduc- 

 tion of the Acephalocyst by buds detached from its internal surface, 

 but to this he added another error, viz. : that in one kind this propa- 

 gation took place by gemmules detached from the exterior of the 

 cyst. The former of these species, or those propagating themselves 

 by the detachment of cysts from the inner surface of the parent, he 

 states to be peculiar to man, and the latter to animals. The former 

 he termed Acephalocystaz endogenic, and the latter A. exogena. 



And it would be as well here, at once, to advert to the difference 

 which really does exist between the cysts of the Echinococcus as found 

 in man and in animals. A difference whose cause I am unable to 

 assign. 



In man, and in the ape tribe,* hydatid cysts are always found en- 

 closed in large numbers, and of very various sizes, in the same cavity ; 

 and these hydatid cysts are always globular and even in their form : but 



* Since this paper was read I have met with an instance of the multiple hydatid 

 in the lungs of a pig. 



