SUMMARY. 89 



tention to what wc know of their life-histories, and especially 

 that part of their history in which water plays some part, we 

 may check the deadly results that often happen. ' 



We must also note how one animal becomes infected passively 

 from devouring another. If we know the various hosts we can 

 often stop the attacks by paying attention to these points, as in 

 the " sturdy " of sheep and the " trichinosis " of the pig, by the 

 prevention of canines getting the diseased brains and pigs the 

 infested rats respectively. Dogs kept free from lice {Tricho- 

 dectes) will have none of those bothering and nauseous little 

 tapeworms to contend with ; whilst if we could only lessen the 

 water-snails {Limnceus truncatulus), or keep our sheep away from 

 them, we should be exempt from the " liver-rot " in our ovine 

 stock. 



In regard to ourselves, it is just as important that meat should 

 be cooked well, so as to destroy the " measly cysts " and trichina 

 germs in pork, as well as tend to lessen the chances of contracting 

 that widespread malady tuberculosis, and that mosquito larvae 

 should be killed to prevent "Filariasis." 



