132 THE MAIN CURRENTS OF ZOOLOGY 



less, experimental evidence proving the truth of the 

 theory was lacking. Dr. Manson (later Sir Patrick) 

 in 1880 was the first to show that the blood of human 

 beings may become infected with a worm-like par- 

 asite (Filaria sanguinis) by the bites of a mosquito. 

 Others as Dr. A. F. A. King (1883) contended on 

 theoretical grounds that mosquitoes carry malaria 

 but adduced no experimental evidence. It was in 

 1894 that Manson communicated his theory con- 

 cerning mosquitoes to Major Donald Ross of the 

 British army and on this suggestion he began working 

 on malaria in India. For more than two years his 

 results were negative because he worked on the 

 mosquito Culex but, turning his attention to 

 Anopheles, he was soon able to trace in this form part 

 of the life cycle of the malaria parasite. Many ob- 

 servers had a part in bringing the demonstration to a 

 conclusion. Grassi, the Italian, did important work 

 (1894), but Ross, with the assistance of suggestions 

 from the work of others, and utilizing their partial 

 results, was able to demonstrate so completely that 

 the malarial parasite is transmitted to human beings 

 through the bite of a particular kind of mosquito, 

 that credit for this great discovery is usually ac- 

 corded to him. 



