H^MATOLCECHUS (DISTOMUM). 45 



Make a drawing showing the above structures as far as you 

 have seen them. 



The Reproductive Organs. Male: Two large bodies, the 

 testes, very definite in outline, occupy the posterior end of the 

 worm. A duct from each, the vas deferens, passes forward, 

 and the two unite just posterior to the point where the intestine 

 branches. By means of a median, common duct, they open 

 to the exterior through the male genital opening. This is situ- 

 ated on the ventral surface, just below the point where the 

 intestine branches. 



Female: Some of the ducts are difficult to see, and in many 

 cases they cannot be followed, but some of the organs can be 

 found in most of the specimens. 



The ovary is a lobed organ lying a little to one side of the 

 middle of the animal, and just anterior to the testes. Lying 

 against it is the sac-like ootype, into which the ovary opens. 

 From the posterior end of the ootype the long, coiled, duct- 

 like uterus passes backward to near the posterior end of the worm, 

 turns and passes forward, and finally opens, at a point on the 

 ventral surface near the male opening. The uterus of an adult 

 worm usually contains embryos and fills the body, so as to ob- 

 scure the other parts. 



The vitellaria consist of numerous small, rounded masses that 

 lie near the margins of the animal. The products of these organs 

 are emptied into the ootype through a short common duct, just 

 ventral to the ootype. Do you know what they are for? Laurer's 

 canal is a short duct which leads from the ootype to the exterior. 

 Its function is doubtful. 



Goto: Studies on the Ectoparasetic Tremetodes of Japan. Jour. Col. Sci. 



Imp. Univ. Tokyo, 8, 1894. 

 Linton: The Process of Egg Making in the Trematode. Biol. Bui., 14, 



1908. 

 Leuckart: Die Blasenwurmer und ihre Entwicklung. 1856. 



: Die Parasiten des Menchen. 



Schauinsland : Beitrag zur Kenntnis der Embryonalentwicklung der Tre- 



metoden. Jen. Zeit. f. Naturwiss. Neue Folge, 9, 1883. 

 Thomas : Development of the Liver Fluke. Quart. Jour. Mic. Sci., 23, 1883. 



