116 Bejjort of the Bilharzia Mission in Egypt, 1915 



liver, where they develop into sporocysts, from which worms escape later into 

 the portal veins. As at post-mortems it is not uncommon to find males, 

 obviously of the same size and age, alone in the portal vein, he assumed that 

 " they must have been generated at about the same time ; this would 

 become comprehensible on the assumption that they were generated in one 

 sporocyst." The female worms which are less common likewise would 

 originate from a sporocyst. Applying these postulates to the ordinary con- 

 ditions found in the Delta, it appeared to Looss that " several miracidia 

 penetrate the body at short intervals and thus males and females will be 

 present." " In this case the females will not have long to wait for fertiliza- 

 tion." While waiting they will have produced a few abnormal eggs but 

 being almost immediately captured by the males are carried off to the pelvic 

 organs, with the result that " there is urinary bilharziosis characterized by 

 the apparition of terminal-spined eggs in the urine ; the same eggs may 

 appear in the f^ces, but the lateral- spined ones will be so scarce that they 

 seem to be altogether absent " [295]. 



In countries where conditions are unfavourable for infection, i.e., 

 where the population is scattered and the people do not bathe in crowds, 

 or where water is scanty or swiftly running, and the chances of miracidia 

 entering the skin are small, then the following train of events may be 

 presumed: " On a single occasion a few miracidia manage to enter the 

 skin and one gets safely to the liver. It produces males. The worms 

 grow to sexual maturity, but finding no females they wait for a certain 

 time and then undertake the journey to the pelvic organs alone. The 

 liver is again free from worms : the infection remains without conse- 

 quences." This may recur as male producing miracidia are so common. 

 Eventually a miracidium enters alone which gives rise to female worms. 

 In due time these " begin to lay lateral-spined eggs. The oviposition goes 

 on, perhaps, for a long time. The number of lateral-spined eggs increases 

 steadily ; all are carried to the liver." Some of these worms may migrate 

 successfully as far as the large bowel. 



Eventually there will be a " strong infection of the liver and some 

 isolated patches in the wall of the intestine, but no terminal-spined ova 

 will ever appear, nor will there be a regular infection of the bladder. 

 After some time, the lateral-spined eggs of the liver begin to appear in the 

 faeces, and they continue being voided in this way for several years." 



Looss details other circumstances under which a secondary' infection 

 with terminal-spined eggs may be contracted by a case showing originally 

 Hanson's intestinal bilharziosis if a sufticient interval has lapsed between 

 the entry of the two miracidia. Lastlj^ infection by a large number of 

 miracidia at a single exposure would result in a pure case of " urinary 

 bilharziosis" [295]. 



Looss concludes that, from his point of view, " no sharp line of 

 demarcation between the two types " exists. " They are simply the 

 opposite ends of a continuous series of intermediary stages" [295]. 



