CONDITIONS INFLUENCING PREVALENCE 215 



And here it may not be out of place to comment on the 

 attitude of those who have been heaping cheap ridicule on 

 those who have been working on this subject. The favourite 

 expedient of this class of humorist is to impute to a man 

 opinions he has never expressed and then to demonstrate 

 how silly he must be to hold such doctrines. Applied to 

 their own persons and profession they would be the first 

 to resent the assumption that the shoemaker is, ex officio, 

 incapable of using a last ; and yet they will have it that 

 the fact of a man making a life-long study of sanitary 

 problems renders him absolutely incapable of forming a 

 rational judgment on the subject. The stock gibe of these 

 good folks is to accuse Major Ronald Ross, and others 

 associated with him, with proposing to "exterminate Mos- 

 quitoes." Now I can assure them that though he labours 

 under what they regard the incurable disability of being a 

 scientific investigator, and a most distinguished one at that, 

 he is, even outside his laboratory, no simpleton ; and no one 

 but a fool would propose so impossible an undertaking, 

 least of all a naturalist who has made a close study of the 

 life-history of these insects. Between this and asserting 

 that it is possible to diminish their numbers there is a very 

 wide gap, though even on this score he has been singularly 

 moderate, for the utmost that he has ever suggested as 

 practicable is to check their free multiplication in certain 

 special localities ; and of the practicability of this there 

 can be no possible doubt. 



While, however, none of us see any immediate prospect of 

 being able to " stamp out malaria " or of wiping out the 

 entire family of gnats, we find in that no reason for sitting 

 with fatalistically folded hands, or of neglecting to utilise 

 every possible method of keeping down their numbers, 

 whether by doing away with every removable breeding 

 place, or by directly destroying the insects in any stage of 

 their existence. The fact is that there still remain numbers 

 of people who regard disease as an inevitable infliction, 

 which can only be dealt with by drugging, and to whom the 

 conviction is strange that every disease must necessarily 

 have a definite cause, which, sooner or later, will be dis- 



