302 FLAT WORMS 



than in S. hcematobium. 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 J inch (13 

 mm.) long. All of these flukes live separately until maturity. At 

 this time the female enters what is known as the gynaecophoric 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 % inch long), and is thread-like 

 and of a darker color. Her two extremities project from the canal of 

 the male in which she lives. 



The oral sucker of the male is infundibuliform and is smaller than the 

 pedunculated acetabulum. In the female the oral sucker is larger than 

 the acetabulum. The eggs of S. hcematobium are fusiform, yellowish in 

 color, have a thin shell and a terminal spine. 



The most prominent symptoms of the Bilharz disease are haemat- 

 uria and bladder irritation; later on calculus formation. 



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

 dysentery. 



There may also be involvement of the appendix. 



In the Japanese infection the symptoms point more to liver and 

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

 in the infection we have fever, urticarial spots and some bronchial 

 trouble (urticarial fever). The eggs should be searched for in the 

 mucus cap on the faeces. 



The eggs of the S. japonicum are readily found in the faeces; they are about 100 X 

 7o/i. They are oval, transparent, and with a smooth shell, within which can be made 

 out the outlines of an embryo. Upon adding water the ciliated embryo begins to 

 show movement in about ten minutes and shortly afterward bursts out of the shell 

 and swims about actively. It is more melon-shaped than the miracidium of S. 

 h&matobium. 



The exact life history is not known of any of these flukes. Looss conjectures that it 

 is probable that the miracidium enters the skin, not requiring 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 subjected to infection. 



Katsurada, by experiments with a cat and dog, has proved that infection will take 

 place through the shaved skin of an animal held in infected water none of the water 

 being allowed to enter by mouth. Fully developed miracidia and the male and 

 female flukes were found in the portal vein. It is thought that further development 

 of the miracidia in the body may account for the heavy infection. 



