SOME INHABITANTS OF MAN 141 



feeding an animal with some of these cysts. A cyst, taken 

 from the brain of a sheep suffering from staggers, was given 

 to a dog ; shortly afterwards the animal was found to be 

 suffering from tapeworms and numerous tapeworm eggs were 

 observed passing in its excrement. Some of these eggs were 

 then fed to sheep. The animals soon showed symptoms of 

 " staggers," due to the pressure of growing cysts on the surface 

 of the brain. 



This successful experiment led Naunyn to feed a dog with 

 one of the large cysts, called " hydatids," which at times 

 produce serious and even fatal disease in man. Numerous 

 minute but sexually mature tapeworms resulted, which proved 

 to be identical with those found in a dog in 1809 by Rudolphi 

 and then believed by him to have arisen by spontaneous 

 generation from the villi lining the intestinal wall. 



Meanwhile Kuchenmeister had continued his observations. 

 Having noted that a marked similarity existed between the 

 hooks borne by the bud in the cystic worms found in pork 

 and those on the head of the common tapeworm found in 

 man, he administered a number of these cysts to volunteers. 

 Later he found that he had successfully infected them with 

 the hooked tapeworm, Taenia solium, thus implicating the 

 pig as the vehicle of the infective stage. Pigs were then fed 

 with eggs from the excrement of a person infected with Taenia 

 solium. When killed later the flesh was found to be infested 

 with typical cysts. 



As no adult tapeworm was found to occur in the intestine 

 of the pig it was evident that the development of the " dropsi- 

 cal " or " cystic " stage was a normal and not merely an 

 aberrant phase in the cycle of the Taenia solium. 



For years it had been observed that among the hooked 

 tapeworms of man specimens sometimes occurred from which 

 the hooks were entirely absent. The generally accepted 

 explanation was that these were old and decrepit individuals 

 which had lost their hooks, just as with advancing years the 

 teeth and hair fall out in man. Leuckart, however, having 

 heard that this type of tapeworm was common among the 

 natives of Abyssinia who do not keep pigs but rear cattle in 



