*ii INTRODUCTION. 



important groups of animals amongst which para- 

 sitism is found are : — the Protozoa, or the ' single- 

 celled ' animals ; the Vermes, or the ( worms ' ; 

 the Arthropoda, or jointed-limbed animals (Insects, 

 Mites, &c.). 



Some members of all these three divisions are 

 found in or on Poultry. The simplest, the Protozoan 

 guests, are at present but little understood. Their 

 small size renders their study extremely difficult ; 

 hence the life-histories of many are still incom- 

 plete. Nevertheless we now know that they are 

 responsible for that pestilential malady, malaria — 

 minute parasitic amoeboid forms in the blood being 

 answerable for its deadly effects. As in man, so 

 in animals and birds — Protozoa undoubtedly cause 

 the liver-rot in rabbits (Coccidiosis), and the majority 

 of cases of Diphtheritic Roup in poultry examined 

 by the author have been caused by similar lowly 

 forms. 



The three chief groups of parasitic worms are 

 known as the Flukes or Trematoda, the Tapeworms 

 or Cestoda, and the Round-worms or the Nematoda. 

 Poultry unfortunately suffer from all three of these. 

 The Flukes and Tapeworms, although much more 

 abundant in species (as will be seen in the list of 

 Poultry Parasites), are not nearly so injurious to 

 Gal/us domesticus as the Nematode worms, for one 



