606 Major Ronald Ross [May 7, 



First let me emphasise the great importance of this practical side 

 of the subject. Malarial fever is spread over nearly the whole of 

 the tropics, abounds in many temperate climates, and has been known 

 to extend as far north as Sweden. In vast tracts of tropical Africa, 

 Asia, America, and of Southern Europe, almost every town and 

 village is infested by it ; millions of children suffer from it from 

 birth to puberty ; and native adults, though they tend to become 

 partially immune, still remain subject to attacks of it. Although it 

 is not often directly fatal, yet it is so extremely prevalent, so endemic 

 in locality, so persistent in the individual, that the total bulk of 

 misery caused by it is quite incalculable. More than this, its special 

 predilection for the most fertile areas renders it economically a 

 most disastrous enemy to mankind. Throughout tropical life, it 

 thwarts the traveller, the missionary, the planter, the soldier, and the 

 administrator. From one-quarter to one-half the total admissions 

 into military hospitals are returned as being due to it ; and it is 

 often the most formidable foe which military expeditions have to 

 encounter. There are reasons for thinking that it indirectly increases 

 the general death-rate of malarious countries by something like fifty 

 per cent. ; and I venture to say that it has profoundly modified the 

 history of mankind by doing more than anything else to hamper the 

 work of civilisation in the tropics. Only those who have studied 

 the disease from house to house, from village to village, can form 

 any true notion of the total effect which it must produce throughout 

 the world. 



Next let us recall Iniefly the various methods which we possess 

 for preventing and reducing the disease. The oldest of these — 

 known to us since the time of the Romans — is drainage of the soil. 

 The reason why it succeeds became quite obvious after 1898 — 

 because it tends to remove the terrestrial pools and marshes in which 

 the Anophelines, that is, the family of mosquitoes which carry malaria, 

 breed. But the new discoveries not only explained the old method, 

 but also rendered it more simple, cheap, and yet precise, by showing 

 us exactly what waters, namely, those in which the larvae of the 

 Anophelines actually occur, are to be drained away, or filled up, or 

 otherwise treated. But science has given us other methods as well. 

 Thus we have known for a long time that quinine is a preventive as 

 well as a cure — that if, for example, a body of men are given quinine 

 with regularity they will suffer less from fever in consequence. Still 

 further, the old saying that the use of mosquito-nets at night will keep 

 off malaria was now fully justified — not because tlie nets exclude any 

 aerial poison, but simply because they exclude the infecting insects. 

 This simple precaution 'can moreover be extended by protecting all 

 the windows of a house by wire-gauze, as already frequently done in 

 the Southern States of America. Punkas and electric-fans also serve 

 to keep away the insects ; and, lastly, segregation of Europeans from 

 native quarters, as used so largely in India, will help to keep them 



