48 THE TAPEWORM. 



From the ovary arises the oviduct, connected with the 

 exterior by the vagina, a duct opening behind the 

 penis. The oviduct is joined by a duct from the yolk- 

 gland, the junction being marked by the presence of 

 numerous gland- cells, the shell-gland. From this 

 junction arises the uterus, a reticulated tube which 

 the eggs enter after being fertilised by spermatozoa 

 introduced by the vagina. In larger segments the 

 uterus extends greatly, but finally breaks down into 

 numerous capsules each containing a bundle of eggs. 

 The egg consists of two shells surrounding a small 

 embryo furnished with three pairs of hooks. 



3. Excretory System. 



This consists of the same type of organ as that found in 

 the Liver-fluke, namely ' flame-cells,' canaliculi, and 

 longitudinal canals. The canals run continuously 

 throughout the whole chain of segments. 



4. Muscular System. 



The longitudinal muscles run throughout the length of the 

 entire organism and break when one or more segments 

 are discharged. Circular and oblique fibres are also 

 present and can be easily seen in transverse sections. 



5. Nervous System. 



This consists of ganglia innervating the muscular scolex, 

 and of longitudinal lateral nerves that supply the 

 muscles of the segments. It is best seen in sections. 



