18 Bejjort oj the Bilharzia Mission in Egijpt^ 1915 



Scliistosomiim hamatohium does not require the services of an 

 intermediary host, and that the miracidium enters the human 

 body directly by penetrating the skin." "I would remark that if 

 S. Immatohium does not require the services of an intermediary 

 host its pecuhar geographical Hmitations are difficult to explain." 

 In the following year Balfour [12] tentatively subscribed to the 

 hypothesis that a minute crustacean was the essential carrier. 

 He says : " In the first report the prevalence of the disease amongst 

 the boys attending a primary school in Khartoum was mentioned. 

 Many of these boys drank from the school well, and this water was 

 submitted to examination. A tiny but very active entomostracean, 

 probably belonging to the order Ostracoda, just visible to the naked 

 eye, was seen. 



" Six active embryos were placed in water along with three 

 of the lively crustaceans and left over night. In the morning one 

 dead embryo was found lying on the foot of the watch-glass, the 

 other five had wholly disappeareci, and the crustaceans remained 

 alive and active. What had become of the missing five? Presum- 

 ably they had entered or been taken up by the crustaceans." 



Two years later (1908), in their " Keview of Eecent Advances 

 in Tropical Medicine " [14], Balfour and Archibald add : " Time has 

 not permitted further experiments with the species of Ostracode 

 mentioned in the Second Report, but certainly the results obtained 

 were suggestive." 

 Looss's IxDi- The practical requirements of his theory of 

 CATIONS FOR direct infection are indicated in the following 

 Pkophylaxis. abstracts from his publications during 1908-14 :— 

 (1908.) Ann. Trop. Med. [295] : " If this conclusion [infection by 

 miracidia] is correct, it leads to the important consequence that 

 the spread of the S. hcBinatohium is not limited by the natural geo- 

 graphical distribution of a special intermediary host. It can spread 

 wherever man carries it, so long as, and in so far as, the climatic and 

 hygrographic conditions are favourable for its development." " The 

 Egyptian peasants usually work their fields in companies ; some- 

 times of two or three, sometimes of several dozens, standing with 

 their feet, and working with their hands, in the water or the mud. 

 They often also bathe in companies in canals with slowly flowing 

 water, pools, etc. One of them who is infected with urinary 

 bilharziosis, when urinating into the water, infects it with several 

 hundreds, perhaps thousands, of eggs. In warm weather the 

 miracidia hatch within a few minutes. They have at once the 

 opportunity of finding a new shelter, either in the skin of the man 



