1909] The Campaign against Malaria. 605 



WEEKLY EVENINO MEETING, 



Friday, May 7, 1909. 



Sir Francis Laking, Bart. G.C.Y.O. M.D. LL.D. 

 Yice-President, in the Chair. 



Major Ronald Ross, C.B. LL.D. D.Sc. F.R.S. F.R.C.S. 



Nobel Laureate. 



The Campaign against Malaria. 



More thau nine years ago I had the privilege of addressing the 

 Royal Institution * on the subject of my researches on the mode of 

 infection in malarial fever ; and I am now called upon to describe 

 what has been done, or not done, in various countries to utilise for 

 the alleviation of the disease the information then obtained. 



The ancients appear to have recognised, not only the principal 

 symptoms of malarial fever, but the fact that it is often connected 

 with marshes : and more recently many authors ascribed this fact to 

 the existence of poisonous vapours which they supposed are given off 

 by stagnant waters, or even by the soil. Still later, a series of patho- 

 logical studies led to the discovery by Laveran in 1880 that the 

 malady is produced by vast numbers of minute protozoal parasites of 

 the red blood-corpuscles ; and students of the subject now con- 

 jectured that these organisms originally inhabited the marshes, and 

 infect man through air or drinking water. My own studies, however, 

 commenced eighteen years ago, and confirmed and extended by many 

 wbrkers, showed that the parasites are carried from man to man by 

 certain species of CulicidaB (gnats or mosquitoes) ; and that it is 

 these carrying agents, and not the parasites themselves, which live 

 in the marshes. Thus malarial fever was now proved to be merely 

 a parasitic disease, the infection of which is carried from man to man 

 by the agency of certain water-breeding insects. 



As described in my previous lecture, the broad principles of this 

 theorem were really fully established by the end of the year 1898. 

 Although numerous minor details still required study — such as the 

 precise species of mosquitoes which carry the infection in various 

 countries, the exact habits of each species, and so on — yet I held that 

 these questions could now be elucidated without difficulty in the 

 ordinary course of work, and that we were already in a position to 

 apply the discovery at once to the saving of human health and life. 

 I propose, therefore, to take up the story again from this point. 



* March 2, 1900. 



