INTESTINAL SCHISTOSOMIASIS 



261 



Diagram of genitalia of a Cestode. ^./.. genital pore: 2 S , male and female 

 ducts opening into genital sinus; c.s., cirrus sac; v.d., coiled vas deferens 

 ("outer seminal vesicle"; va^., vagina; sem. rec, seminal receptacle; sp.d., 

 spermatic duct; C.c, fertiiiEation canal; vit. d., vitelline duct; sh. g., shell 

 gland; ut. c, uterine canal; nt., uterus; Ov,, ovary; /., pumping organ. 

 (Stephens.) 



The vas deferens opens dorsally and the vaginal opening lies 

 immediately behind it. The rosette uterus has four to six convolutions 

 and has its separate opening. 



The six-hooked onchosphere passes into the fish. 



When the fish is eaten, adult worms are formed from the oncho- 

 sphere, and the eggs are passed into the faeces in twenty-four days. 



The Qgg has an operculum, this is the only exception. The opercu- 

 lum is, of course, common in trematodes. 



The onchosphere has no sucker. 



The parasite is found in Switzerland, N. E. Europe, and Japan. 



The infection by it produces a severe anaemia with fever and a 

 quick pulse. 



SPARGANUM. 



This is a term applied to the larval stages of Dibothriocephalidae, 

 which are too premature for their genera to be known. 



S. prolifer is i to 12 mm. long by 2*5 mm. broad. The head is 

 motile and can be invaginated. An apical depression serves as a 

 sucker. It can multiply by transverse fission. No genitalia are seen. 

 The adult is unknown. 



The parasite produces subcutaneous nodules in the fascia of muscles 

 and the abdominal cavity of man. There may be an universal acne- 

 like itching eruption. 



A parasitic c}'st usually contains one or two worms, a watery, 

 jelly-like or opaque substance. The worms may be encapsulated in 

 the cysts and may thus survive in man for years. 



