DISEASES OF CATTLE. 53 



On being told that man also obtains such a parasite from eating 

 beef, he was completely surprised. 



The name which science has given to this parasite is Taenia 

 medio-canelldta, or, better, saginata. 



This parasite exceeds in length that which we have previously 

 described as being obtained from pork. Its sections, or proglottids, 

 are also broader and thicker. Tcenia solium, or armata, derived 

 from pork, has its scolex, or head, armed with hooks, which is not 

 the case with the one we are at present considering. This fact at 

 first led naturalists to think they had before them one and the same 

 tape-worm, the differences in appearance and formation of the heads 

 representing different stages of development, the armed parasite 

 representing a youthful, the unarmed an aged, period in its exist- 

 ence. This has been clearly demonstrated to be a mistake. Pro- 

 glottids of taenia saginata fed to young swine failed to produce cys- 

 ticerci, or measles, while the same when fed to calves were followed 

 by positive results — i. e., the development of cysticerci of the un- 

 armed tape-worm in the interfibrillar tissue (Leuckart, Mosler, et al.). 



As to their presence in cattle, Dr. Thudicum * says : 



" The question why the cysticerci of taenia saginata have never 

 been observed in the flesh of cattle, with the exception of those 

 cases in which they have been intentionally reared, is of great inter- 

 .est and importance, from a sanitary point of view. It is possible 

 that these bladder-worms are present in the musculature of cattle in 

 very small numbers only, and consequently do not present any such 

 striking appearance on section of the muscles as is produced by 

 measles in the muscles of swine. For while a pig would devour an 

 entire tape-worm if it came in its way, a calf would refuse to eat it, 

 if it could avoid doing so ; hence, only free eggs or single proglot- 

 tids, adhering to or concealed in the herbs making up the ordinary 

 food of cattle, could be introduced into their systems. Thus, cattle 

 driven along a road or path would be liable to snatch a mouthful of 

 grass, and with it a proglottid of the hookless or five-cupped tape- 

 worm. The very circumstance of the scarcity of cysticerci in the 

 flesh of cattle facilitates their importation into the human intestines. 

 The single specimens are not discovered, and consequently not 

 avoided ; hence, the taenia derived from them live in almost all 

 countries of our globe, and infest the black and white man, the 

 Mongol, the Malay, and the Indian. I have examined many thou- 

 sands of specimens of beef from many hundreds of bodies of beeves, 

 and have never yet found a cysticercus of this taenia in the flesh or 



* Report to the Privy Council of Great Britain. See seventh report, London, 1865. 



