12 Beijort of the Billtarzia Mit>6iou in Egypt, 1915 



free-swimming luiracidia in contact with the same molluscs without 

 obtaining an infection. It is easy to infect molhiscs with miracidia 

 of species which actually develop in them. Bilharzia miracidia 

 were never seen to take any notice of any mollusc in their neigh- 

 bourhood, whereas others developing in a certain mollusc soon 

 begin to swarm about it, and may, under the microscope, even be 

 observed to enter into it. The same negative results were observed 

 with larvse of insects, with fishes, and with plants. I am thus 

 forced to the conviction that man himself acts as an intermediar}' 

 host." 



"In man, the miracidium must develop into a sporocyst which 

 either directly or indirectly generates the Bilharzia worms. The 

 only organ of the body thus far known to harbour young, and some- 

 times very young worms, is the liver. I therefore conclude that 

 the liver is the habitat of the sporocyst from which the worms later 

 escape into the portal vein." 



In 1909, in a controversial paper entitled " Bilharziosis of 

 Women and Girls in Egypt in the Light of the Skin Infection 

 Theory," Dr. Looss [296] replies dogmatically to some brief 

 comments on the insufficiency of his hypothesis made by 

 Drs. Elgood and Sandwith at the Annual Meeting of the British 

 Medical Association: — 



" Any theory about the mode of infection with bilharziosis, in 

 order to be at all acceptable, must («) account for the passages of 

 the miracidium both from man to water and from water back to 

 man ; it must (b) duly consider both the habits of the host and the 

 biological peculiarities of the parasite. 



" The theory of miracidium infection by the skin is in accordance 

 with all the facts thus far known (a) of the biology of the parasite, 

 (6) of the distribution of the disease among the population (native 

 and foreign, town and rural) of Egypt. It shov/s (c) how the chief 

 sufferers— the children in town, the adult males in the country — 

 live under conditions which, from the epidemiological point of view-, 

 are essentially the same, and give the miracidia (d) the opportunity 

 of passing, within the short time of their life, from man to water 

 and from water back to man." 



In a popular lecture [297] on the " Life-history of the Bilharzia 

 Worm," before the Cairo Scientific Society in 1910, Dr. Looss again 

 declared : — 



" What we know- of this, the life-history of the parasite, is the 

 following : — 



"The worms which mfect a fresh subject originate from the 



