xiv INTRODUCTION. 



die. Partial parasites are those that only go to their 

 host to feed — as soon as they have taken sufficient 

 nourishment leaving their ( object of robbery ' to 

 sleep off the result of their meal in some quiet and 

 -ccluded spot. The Poultry Flea and the prejudicial 

 Red Hen-Mite have this irritating way of living. 



One point economically of no little importance in 

 parasites is that they may require two k hosts ' in 

 which to develop, and occasionally one of those hosts 

 happens to be man. Taenia solium, the dreaded 

 human Tapeworm, is one of these ; it comes from the 

 diseased pork known as ' measly pork,' the flesh 

 of a pig that has eaten the cast-out proglottides or 

 segments (full of eggs) of the human Tapeworm, the 

 effffs from which are changed into the peculiar 

 and repulsive ' bladder-worms ' or cysts in the pig's 

 muscle, which on being eaten by man again become 

 Tapeworms. Similarly, Trichinosis is taken by 

 human beings by eating the flesh of pigs suffering 

 from this disease. 



Such facts as these make us chary of what we eat. 

 All the more satisfactory is it, then, for us to know 

 that, out of all the innumerable Poultry Parasites, 

 none (so far as we know) are hurtful to us. 



Not only do parasites sometimes destroy their host, 

 but they stunt the growth if they commence their 

 attack on young subjects. It is extraordinary how a 



