ig8 FLEAS, FLUKES AND CUCKOOS 



Flukes (Trematoda) 



Bird flukes (class Trematoda, sub-class Digenea) are colourless, leaf- 

 shaped worms, generally only a few millimetres in length, which live 

 inside the various organs of the host's body. They feed on blood and 



Dragonfly, Lihellula quadrimaculata, 

 an intermediate host of the oviduct fluke (x . 66) 



lymph and other fluids and exudates and also possibly on cells of the 

 mucous membrane lining their particular habitat. They attach them- 

 selves by means of a sucker surrounding the mouth and also by a second 

 sucker when this is present, situated on the ventral surface of the body. 

 The reproductive system of flukes is fantastically complicated. Except 

 in one family, male and female organs are present in the same individual 

 and self-fertilisation is the rule. When a worm is preserved and stained 

 with various dyes, the different parts of the reproductive system can 

 be clearly seen forming intricate and gorgeous patterns. No 

 objective person can deny that the egg-shell producing glands of a 

 trematode worm are aesthetically satisfying. The excretory system is 



