58 THE INTERNAL PARASITES OF 



bones of men and animals, are liable to be invaded by 

 these bladder worms ; and I may mention the singular 

 circumstances that no less than nine instances have been 

 brought under my notice where the hydatid had lodged 

 within the shaft of the human tibia. In the case of 

 animals such occurrences must be rare ; nevertheless, 

 John Hunter secured two remarkable examples of this 

 parasite from the bones of oxen. In one animal an 

 echmococcus vesicle occupied the humerus; whilst in 

 another several " acephalocysts " were seated within the 

 iliac bone. These remarkable specimens are still 

 preserved in the museum of the Eoyal College of 

 Surgeons, Lincoln's-inn. 



The abundance of common hydatids, or acephalo cystic 

 bladder worms, in cattle has already been alluded to; and 

 my correspondent Dr. Joseph Fleming rightly. accounts for 

 their great prevalence by referring to the multitude of 

 dogs which frequent the Indian villages. He says : — 

 "I calculated there must be one dog to every four 

 inhabitants, and I considered it strange that these dogs 

 had no owners. In short, they appeared to form indepen- 

 dant colonies in every village." I will here only further 

 add, that the true relation subsisting between these 

 bladder worms and the echinococcus tapeworm will be 

 more fully shown in the sequel. 



The Slender -necked Hydatid. — This parasite (Gysticercus 

 tenuicollis) is far less abundant in the ox than in the 

 sheep. Its presence in the bovine bearer often escapes 

 observation, chiefly because the parasite rarely occasions 

 inconvenience to the host. As I shall show, however, 

 when treating of the entozoa of the sheep, the slender- 

 necked hydatid is sometimes capable of causing inflam- 

 matory action, especially when it takes up its abode in the 



