BILHARZIASIS. 1 99 



The lateral-spined ovum is also found in the faeces. In the West 

 Indies, as shown by the reports of Surgeon Holcomb from Porto Rico, 

 rectal bilharziasis is rather common. In these cases the egg is prac- 

 tically always lateral-spined. The adults of this species, the S. 

 mansoni, are scarcely, if at all, to be distinguished from the S. haema- 

 tobium. With the S. japonicum, the name of the Eastern species, there 

 is not only the difference in that the eggs are without spines, but, in 

 addition, the skin of the adult parasite is nottuberculated,as is the case 

 with the other two species. Catto considers that the S. japonicum may 

 live in both arteries and veins. The other two species only live in 

 branches of the portal vein. The blood flukes are about 1/2 inch 

 long. All of these flukes are hermaphroditic, but live separately until 

 maturity. At this time the female enters what is known as the gynaeco- 

 phoric canal of the male; this canal is formed by the infolding of the 

 sides of the flat male fluke, thus giving a rounded appearance to the 

 male. The female is longer than the male (about 5/6 of an inch long), 

 and is thread-like. Her two extremities project from the canal of the 

 male in which she lives. 



The most prominent symptoms of the Bilharz disease are haema- 

 turia and bladder irritation; later on calculus formation. In rectal 

 bilharziasis the symptoms are more those of bleeding piles or of a mild 

 dysentery. In the Japanese infection the symptoms point more to 

 liver and spleen, there being ascites, cachexia and a bloody diarrhoea. 



The life history is not known of any of these flukes. Looss con- 

 jectures that it is probable that the miracidium enters the skin, not re- 

 quiring an intermediary host. Frequent experiments have failed to 

 show any mollusk, etc., which attracted the embryo. Evidence seems 

 to show that those who are constantly wading about in the water 

 of the pools or the mud of the fields are the ones most subject to 

 infection. 



If urine containing eggs is diluted with water the miracidium 

 breaks out of the shell and swims about as if in search of some 

 desired object. 



The views are also entertained that the miracidium may gain access 

 to the body through the drinking water; there is much evidence against 

 this. However access to the body is gained, it is known that the larval 



