99 



brain and the sub-cutaneous tissue ; and it is the more- 

 dangerous stage of this parasite. 



State briefly the Life- Histories of Taenia serrata and Taenia 

 canina or cucumerina (syn. Dipylidium caninum). 



Taenia serrata is a common tapeworm of the dog. The 

 shed proglottids are swallowed by rabbits and hares while 

 feeding. Via the stomach wall and the portal vein, thfr 

 embryo enters the liver and passes to the omentum, where 

 it attaches itself and becomes a bladder-worm, Cysticercus 

 pisiformis. When the viscera of an infected rabbit or 

 hare are eaten by a dog, the bladder-worms are intro- 

 duced into the gut and the tapeworm is then developed. 



Taenia canina (syn. Dipylidium caninum) is the com- 

 monest tapeworm in the dog. It is also recorded as occurring 

 occasionally in Man (in children). Its larva is a Cysticercoid 

 (i.e., a bladder-worm which has a small bladder with a 

 slight or obliterated cavity and a solid tail-like portion 

 that is ultimately cast off) and it lives in the dog louse- 

 ( Trichodectes canis), the dog flea ( Ctenocephalus canis}, 

 and the flea of Man (Pulex irritans). The infection of 

 dogs and cats is brought about by biting or swallowing 

 their own lice and fleas ; transmission to human beings 

 may be effected if an infested dog or cat happens to lick 

 the face or hands of a child. 



Give short Accounts of Taenia saginata and Taenia coenurus.. 



The Beef Tapeworm (Taenia saginata, syn. T. medio- J 

 canellata) lives exclusively in Man, in the small intestine. 

 It attains an average length of from 4 to 10 metres. The 

 scolex is cubical and has four suckers ; and, instead of 

 a rostellum, there is an unarmed sucker-like organ. The 

 larval stage, Cysticcrcus bovis, lives in the ox, and it is 

 transmitted to Man when "measly" beef is eaten raw or 

 under-cooked. This is the commonest tapeworm of Man ; 

 its growth is exceptionally rapid, and the proglottids 

 have the power of independent movement. 



Taenia coenurus is a common tapeworm in sheep-dogs. 

 When mature its average length is about twelve inches- 



