26 



Rats and Mice 



execution among rats ; but their powers have Umitations, and they 

 form no sort of just equivalent for the wild carnivora we have lost. 



Even if we still possessed our full quota of carnivorous creatures, 

 it is more than doubtful whether that would relieve us from anxiety 

 in this matter. Our enterprise in engineering and building has 

 provided the rat with a measure of shelter and security infinitely 

 greater than the best that could be afforded it by Nature. Against 

 rats in such strongholds carnivora could do but little. 



We cannot, however, deprive Nature of her second weapon : 

 infectious disease is always present, if latent, among rats as among 

 men. But we dare not let Nature invoke disease ; for should she 

 do so, that disease will in all probability smite man no less than 

 the rat. For this reason our public health authorities work hard 

 to preserve the rats in good health. As soon as they observe 

 mortality from unknown causes among rats they look for plague ; 

 if, as often happens, they find plague, they endeavour to protect 

 the rats of other places by first isolating and then exterminating 

 the infected colony. Biology has sought and is still seeking a 

 disease which will kill rats but be harmless to man and his 

 domestic animals ; that search has not yet been rewarded, although 

 results of great promise have been obtained. Promise is one thing, 

 fulfilment another ; the disease weapon to our liking may not be 

 fashioned before we have felt the sting of one of those already 

 existing in the armoury of Nature. 



What then is to be done ? Are we so destitute of resource that 

 we must be content to wait for that punishment inevitably ours if 

 we do not find a method of redressing the balance of Nature so 

 light-heartedly disturbed? The answer to the latter question is 

 simple. Although there is no royal road to such an end, we 

 possess ample means of exterminating the rat if we have the mind 

 to do so. These means, however, will not avail until everybody 

 in this country is convinced of the necessity of using them 

 whenever and wherever possible. There are six indispensable 

 co-efficients upon which the success of whatever means we may 

 adopt will depend; these are organization, co-operation, deter- 

 mination, time, money, and labour — the way of the transgressor is 

 hard. Of course, science may shorten the road for us, but not 

 without further biological research of all kinds. That, however, 

 again costs time and money ; and so many have yet to learn that 

 all branches of science are valuable and interdependent, that in 

 reality there are not two kinds of science — one called " applied," 



