MALARIA 243 



the ages, with their sufferings mitigated, it is true, 

 for the last three centuries by the possession of 

 quinine, one of the greatest discoveries of empiri- 

 cism. A few years of experiment, however, and we 

 learned enough of the natural history of this disease 

 to be able to say that if administrative action were 

 prompt and comprehensive enough no man need 

 suffer from it again. 



For some years after Laveran had described 

 the parasite of malaria in the blood of patients it 

 seemed as if little use could be made of the discovery, 

 because the disease could not be communicated 

 to animals, and so experiment seemed impossible. 

 Then at last came the thought of Manson, the work 

 of Ross, and the discovery that the mosquito is 

 the c intermediate host' of the parasite and the 

 means of its transmission. The life-cycle of the 

 latter was then worked out, and the whole subject 

 of malaria so fully clarified that a control of the 

 scourge has become a matter for organisation and 

 administration alone. Later studies have added 

 instance after instance of a disease having more or 

 less similar relations. Knowledge of pathogenic 

 protozoa, of the existence and nature of interme-: 

 diate hosts, of transmission by bites of vermin, 

 and of other significant facts, has robbed another 

 group of diseases of its terror and is making the 

 tropics habitable for all men. Our country may 

 well be proud of its share in this great advance. 

 It forms a triumph of science which should receive 



