HYMENOLEPIS NANA 



227 



reported from Russia, Servia, England, France, Germany, South 

 America, Siam and Japan. Notwithstanding its small size this 

 worm causes considerable disorders in its hosts mostly children 

 as it sets up loss of appetite, diarrhoea, various nervous disturb- 

 ances, and even epilepsy ; all these symptoms, however, disappear 



FIG. 153. Hy- 

 menolepis nana (v. 

 Sieb.), about 12/1. 

 (After Leuckart.) 



FIG. 154. Head of Hyme- 

 nolepis nana, with rosteilum 

 retracted. 100/1. (a) A single 

 hook. 600/1. (After Leuckart.) 

 (6) An egg, highly magnified. 

 (After Grassi.) 



II rl &&?:? 



V^"-* s & : i'i 



*<,/.V:-V/vv.W 



FIG. 155. Longitudinal 

 section through the intes- 

 tinal villus of a rat, with 

 the cysticercoid of Hyme- 

 nolepis murina( magnified). 

 (After Grassi and Rovelli.) 



after the expulsion of the parasites, which are generally present in 

 large numbers. 



The development as well as the manner of infection is still 

 unknown ; Grassi certainly is of opinion that Hymenolepis nana is 

 merely a variety of Hym. murina (Duj.) which lives in rats. 

 According to Grassi direct development takes place by means of 

 the omission of the intermediary host, but with the retention of 

 the cysticercus stage, that is to say, rats infect themselves with 

 Hymenolepis murina direct, by ingesting the mature segments or 



