APPENDIX I. 



THE PREVENTION AND TREATMENT OF VERMICEOUS DISEASES. 



Although we have seen in chapter v. that some worms (Anguil- 

 hilidse) occasion considerable harm to certain crops, yet it is 

 amongst our stock that their ravages are mostly felt, especially in 

 sheep and horses. As the loss that many worms are accountable 

 for often reaches very serious dimensions, a few general notes on 

 the prevention and treatment of these parasitic diseases may not be 

 out of place here, after having dealt with their economic history in 

 preceding chapters. The three most important gi-ou^Js of the 

 parasitic worms are the Tapeworms, Round- or Thread-worms, and 

 Flukes. Tapeworms often cause severe diseases in animals and 

 man. When we know the life-history of a species it is usually easy 

 to prevent the increase, if the trouble is taken to do so ; but where 

 we are ignorant of the various stages and habitats of the pests, 

 remedies only lie in our power. As pointed out in chapter iv., 

 nearly all tapeworms have two distinct hosts — one in which the 

 adult sexual tapeworm lives in the intestines, another in which the 

 asexual cyst or bladder-worm takes up its abode. The cysts are 

 usually found in carnivorous and omnivorous animals, in the various 

 organs and internal membranes. Each cyst may give rise to one or 

 hundreds of adult worms, in another animal, on being eaten. By the 

 destruction of these cystic parts the tapeworm stage is prevented, 

 and the tteniosis is stopped from spreading. For instance, if all the 

 heads of " pothery " or " sturdy " sheep are destroyed (and some- 

 times in lumbar-gid the posterior spinal cord) with the coenuri in 

 them, so many hundreds of Tcenia cmnurus, one of the dog tape- 

 worms, are destroyed. Again, if the diseased pork called " measly 

 pork" is not eaten by human beings, the dreaded human tape- 

 worm, T. solium, is prevented. 

 The destruction of all flesh containing the cysts or water-bags 



2 H 



