11 



species of the T&nia vesicularis properly so called, or of those singu- 

 lar hydatids which I have remarked and described in the livers and 

 lungs of calves and sheep, and which ought certainly to be attributed 

 to a living creature, and which are evidently organized, at least as far 

 as regards the interior pellicle, which is studded with granulations." 

 And he remarks that "the vermiculi, furnished with a coronet of hooks 

 and four stigmata, which are enclosed in the vesicles, are possibly a 

 development of the globules which I had remarked (on their inner 

 surface.)" 



Pallas seems also to have been aware of the great similarity, if not 

 of the identity, of the hydatid of man with that of animals, and of the 

 different states in which they are found in each case. 



The next writer who describes these animals is Goeze, in 1782, 

 who very accurately describes the appearance of the animal and the 

 situation and form of the hooks. He arranged them between the Cys- 

 ticercus and the C<enurus, and he points out the differences between 

 them and the latter, with which Pallas had been inclined to confound 

 them. He was of opinion also, that the vermiculi were connected to 

 each other by a membrane or mucous pellicle, and that they had no 

 adherence to the walls of the cyst : an error maintained, as we shall 

 see, by later writers, and even by M. Livois himself. 



In 1796, however, this adherence was observed by Blumenbach, in 

 hydatids from the lungs of an ape. 



In 1800 Zeder gives an account, though rather a confused one, of 

 hydatids in the brain of a woman, and he makes it a species of Cysti- 

 cercus. Up to this period it appears to have been the universal 

 opinion that hydatid cysts always contained these animalcules, and 

 the first writer of note who threw doubts on this subject was Laennec 

 in 1804, who gives a most accurate description of the hydatid cyst, 

 and the granulations which he observed adherent to its walls. He 

 describes the granulations as composed of several individual vermiculi, 

 which under the microscope he says are very nearly like the Cysticer- 

 cus. He remarks the presence of the small, transparent, ovoid bodies 

 in their interior. He was unable to determine their mode of adhe- 

 rence to the walls of the parent cyst, though he observed in one or 

 two a sort of filament, which hung from the posterior part of the body. 

 Laennec drew this description from hydatids taken from the liver of 

 sheep. After reading this, it appears very extraordinary that he 

 should have made the mistake he did when he came to examine the 

 same creature in the human subject. He had already remarked the 

 exact resemblance that the cysts in both cases bore to each other, 



