19 io.] The Destruction of Rats. 735 



they find that any number of their fellows die after eating 

 any kind of food they will avoid such food for some time. It 

 will be as well, therefore, to vary the form and appearance of 

 the poisoned bait at intervals. Thus, after using poisoned 

 bread for a while, oatmeal similarly treated should be used. 



Apart from the risk of a possible prosecution under the 

 Acts which deal with the use of poisoned grain, meal, or meat, 

 it is very necessary when using poisons to take precautions 

 to avoid injury to other animals and human beings. (The 

 Acts concerned are the Poisoned Grain Prohibition Act, 1863, 

 and the Poisoned Flesh Prohibition Act, 1864.) 



In any case poisoned baits should only be laid by authorised 

 and responsible people. Their whereabouts should be care- 

 fully recorded, and they should be visited regularly and 

 destroyed if not taken within a short period. The strictest 

 precautions should be taken to prevent the bait being eaten 

 by domestic animals, and if necessary notices should be 

 exhibited in places where baits are laid to warn people to keep 

 dogs or other animals away from the place. When poisoned 

 baits are laid by a Rat Club or other organisation, it would 

 be as well to insist that each. group of baits should be num- 

 bered, and its situation, success, or failure and ultimate 

 destruction recorded in a book. 



Rat viruses, on the other hand, of which there are several 

 on the market, can be used without fear of direct injury to 

 any animals other than rodents. These viruses are believed 

 to be composed in every case of a culture of a microbe causing 

 a specific disease of rats, which in some cases at any rate is 

 contagious, so that the inoculated rat conveys the disease to 

 his fellows. The uncertainty with which this method is 

 attended is due partly to the difficulty of securing a successful 

 infection in all cases, and partly to the fact that, if only 

 slightly infected, rats recover and thereafter become more or 

 less immune to the disease. 



It cannot be too strongly urged, therefore, that if there is 

 to be a successful attack upon rats in any district, reliance 

 should not be placed in any one of the methods referred to 

 above, but that as far as is possible under the circumstances 

 all these methods should be employed. Rats are intelligent 

 animals, and will soon learn to evade any one of these devices, 



