46 THE TAPEWORM. 



Nearly all dogs contain tapeworms, and isolated segments 

 are easily obtained alive after defalcation. They should be 

 examined after clearing in glycerine and also fixed with corrosive- 

 acetic mixture, washed in 70 per cent, spirit, and either stained, 

 cleared, and mounted or cut into transverse sections. To 

 obtain a complete chain of segments, and especially the scolex, 

 a post-mortem must be made of a freshly killed dog or cat. 



1. General Structure of the Commonest Dog-tapeworm. 



The * scolex ' or attached end is a mobile, muscular, conical 

 structure supporting four suckers and five circlets of 

 minute hooks, but with no mouth or sense-organs. 

 It is followed by the ' neck,' the region of greatest 

 growth continually producing ' segments ' or ' pro- 

 glottides.' There is no trace of an alimentary canal. 



Each segment contains two sets of hermaphroditic reproduc- 

 tive organs, but as the male organs mature before the fe- 

 male ones, the appearance of the segments undergoes a 

 gradual change as they are pushed further and further 

 away from their origin in the neck-region. 



At first each segment develops the male organs, at a later 

 stage of growth its female organs appear, still later the 

 female organs ripen, and lastly the organs consist of 

 fertilised eggs, the male and accessory female organs 

 having degenerated. 



2. Reproductive System. 



Examine segments which have been cleared or stained and 

 mounted. 



The testes consist of minute follicles scattered over one 

 surface (so-called dorsal). They are united by exces- 

 sively minute canals into two coiled ducts the vasa 

 deferentia. which open on the margin of the opposite 

 side of the segment, each by an eversible penis. 



The female glands on each side consist of a deeply lobed 

 ovary lying internal to the penis and a yolk-gland 

 behind it. 



