Sir Ronald Ross 223 



from India. The meeting " unanimously passed a resolu- 

 tion sending Major Ross the Members' congratulations on 

 a great and epoch-making discovery/ ' 



Ross had won, but still the last link in the chain of 

 evidence had to be forged. Ross had carried out his 

 experiments on birds. It was very probable that human 

 malaria followed the same cycle. But there was as yet no 

 absolute certainty, and could not be until the tests had 

 been carried a step farther. 



In the malarial region of Italy others seeking proof had 

 infected human beings with malaria by means of mos- 

 quitoes, but there was also the night marsh air, the hot 

 climate, and other possible sources of general infection. 

 Manson decided to demonstrate the value of Ross's dis- 

 covery once and for all by bringing mosquitoes infected 

 with the malarial parasite to London, where there was no 

 malarial fever at all, and there infecting human beings by 

 means of the insects. 



Several small cages covered with fine netting were con- 

 structed, and in these the infected mosquitoes were hurried 

 across Europe to London. There they were allowed to 

 bite two men who had volunteered to contract malaria 

 in order that the last link in the chain of evidence might 

 be forged. The first of these men was Manson's son, 

 P. Thornburn Manson. He was exposed to the insects on 

 August 29th, 1900, and again two days later. Anxiously 

 Manson and his colleagues waited for the period of 

 incubation to expire. The proof was forthcoming. 

 Young Manson began to have fever on September 13th, 

 and on the 17th the parasites of the disease were found 

 in his blood. 



The second volunteer, Warren, was exposed later. He 

 too contracted malaria. This experiment helped to con- 

 firm the fact for the whole medical world. As Ross has 

 written, " a more brilliant verification of them could not 

 have been devised." 



