Bearing of Previous Work on B. japoxica and Concluding 

 Eemarks. 



Given the premises laid down b}^ Looss as a result of prolonged study 

 of local conditions in Egj'pt, his theory, " based upon a large number of 

 anatomo-pathological and helminthological facts deliberately weighed and 

 compared," could not be overthrown simply by an argument from analogy. 

 If it were otherwise, those who accepted and supported his views bear a 

 heavy responsibility for failing to apply the analogies resulting from the 

 experimental data afforded by experiments with B. japonica ; the first and 

 most fundamental of which, made by Fujinami and Xakamura in 1908, 

 excluded, for this allied species, the possibility of direct transmission. 



In the opening section of this report, I have traced the evolution of 

 scientific opinion regarding the mode of spread of Bilharzia hcemafobia. 

 The analogies presented by B. japonica have there been referred to only 

 to show how these were definitely set aside by the exponents of the theory 

 of direct infection in Egypt. I have refrained from using them as an 

 a priori argument, because in the proved facts of the life cycle of another 

 common Egyptian parasite of man there was a strong opposing analogy, 

 in support of the possibility of an exceptional occurrence of direct infection 

 among parasites requiring usually an intermediate host. Hijmenolepis nana 

 has been shown experimentally to be capable of direct transmission although 

 the other members of the genus have arthropod intermediaries. 



Moreover, the object of my own work has been to arrive at a solution 

 of the various problems, presented by the bilharzial diseases in Egypt, by 

 direct observation and experiment, rather than by the inductive method. 



I propose to relate now the various published facts concerning the life- 

 history of jB. japonica that were available at the outbreak of war ; to 

 show in what respects these failed to afford the data necessary for a rapid 

 solution of tbe bilharzia problem in Egypt and in what way my own 

 investigations on this Oriental species, while confirming previous con- 

 clusions of Japanese observers, gave a new method by which the infective 



