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There are: — 



(1) Natural Enemies. 



(2) Food Poisons. 



(3) Virus Remedies. 



(4) Carbon Bisulphide. 



Natural Enemies. — I have been able to gather but little informa- 

 tion on this point. The life history and habits of the native rat 

 are poorly known. The natives could not tell me with any certainty 

 where the animal goes when it leaves the paddy fields; probably 

 it migrates to the houses and to the jungle, the paddy field being 

 its main breeding-ground. In the course of the experiments 

 I turned out two nests containing eight and nine respectively, which 

 were less than nine days old. It would be useful to know more 

 about its breeding habits. The best known natural enemy is the 

 mongoose. There appear to be very few carnivorous birds in the 

 Peninsula which attack rats. At any rate the natural enemies seem 

 to be ineffective, and as we do not know much about them nothing 

 can be done to encourage them. 



Food Poisons, — There are several of this class, but phosphorus 

 or arsenic is the usual effective agent in all. There are many 

 objections against them. They may poison natural enemies of 

 rats, or domestic animals, and it is undesirable to put them at all 

 in the hands of native peoples. Besides the rat has its choice, 

 it may refuse to eat them, and probably will do so when they are 

 put in rice fields. I have not yet been able to carry out experi- 

 ments on this point. As exterminators they are, for our purposes, 

 only less useless than the natural enemies. 



Virus Remedies. — The " Liverpool" Virus has got a good repute 

 at home, so has the " Danyzs," the Pasteur Institute Virus. There is 

 another called "Ratin," possibly "Liverpool" is a new name for it. 

 They are apparently contagious diseases due to a definite organism. 

 As far as I can gather viruses have been a failure out here. 

 The organism may have died on account of the time that elapses 

 from its despatch until it is received here, or it may have suc- 

 cumbed to the heat of a tropical sea voyage, or it may be that the 

 race of rats in this country are immune to these viruses. They 

 have the advantage that there is no danger and little trouble in 

 their application, and that the rats have little choice of escape 

 once a few have been infected. 



I should like to have more information as to how the " Liverpool" 

 virus, for example, works in grain fields at home. It must be 

 applied on cubes of bread which may be quite effective about 

 buildings, where rats eat all sorts of garbage, but may be of less 

 efficiency in paddy fields. 



I hope to give these remedies a fair trial immediately and to be 

 in a position to report definitely on them before the beginning of 

 the next paddy season. 



