9'2 Beport of the Bilharzia Mission in Egypt, 1915 



sucker is absent, in the latter it is well developed. It is to this 

 latter group that the Bilharzia cercariae belong. The following 

 furcocercous cercariae were found : C. vivax in Cleopatra ; C. fissi- 

 cauda in Bullinus ; a form very similar to C. ocellata in Melania, 

 Planorbis hoissiji and P. mareoticus, which we provisionally called 

 " C. hilkarziella " ; and the cercariae of bilharzia in Bullinus and in 

 P. hoissyi. C. vivax and C. jissicauda both possess a muscular 

 pharynx behind the oral sucker, in the' other forms this is absent. 

 " C. bilharzia " and "C hilkarziella " are related and probably belong 

 to closely allied genera in the family Bilharziidae. " G. hilkarziella " 

 possesses a pair of pigment spots anterior to the ventral sucker 

 and there is a cuticular keel along each side of the prongs of the 

 tail. These are absent in the Bilharzia cercariae. 



The relation or identity of the Bilharzia cercariae found in the 

 molluscs Bullinus and Planorbis will be discussed in the articles 

 dealing with the adult worms. 



Skin Infection. 



Experimental evidence has already been given (p. 44) in favour 

 of the direct penetration of the skin and of the mucous membrane 

 of the mouth and gullet by the Bilharzia cercaria. Many writers 

 appear to have the greatest reluctance in accepting the possibility 

 of skin penetration. Some, like Allan, believe that infection is 

 limited to the tender skin of the prepuce and advocate universal 

 circumcision ; Buffer and others interpret infection during immer- 

 sion in Bilharzia-infested countries as due to entrance of the 

 cercaria through the anus. 



In the United States Naval Medical Bulletin for October, 1915 

 (p. G48), Post writes that our experimental infection of rats by 

 immersion " clearly shows, it seems to me, that the most usual 

 port of entry must be the anus." 



It may be pointed out, however, that : (a) Certain cercariae are 

 known to penetrate the tissues of the second intermediary host to 

 encyst, and are provided with special glands and, in some cases, 

 stylets to enable them to do this. (6) If a young rat or mouse 

 be suspended in a large test-tube containing water full of Bilharzia 

 cercariae, these cercariae can be seen to approach and fasten on to 

 the limbs and body of the animal. When the animal is removed 

 half an hour later, there remain in the fluid only a few cercariae and 

 a large number of detached tails, (c) A young mouse so immersed 

 for half an hour was killed, and subsequently embedded whole in 



