Roberton. — Malaria and Mosquitos. 231 



work on the subject. On his return to India Ross set to 

 work at long and patient investigations which were finally 

 crowned with success. He proved definitely that mosquitos 

 were the carriers of malaria, and pointed out the way in 

 which infection through them happened. Ross's full story, 

 apart from his scientific work, has not yet been published, 

 but enough is known of it to enable us to assert that it 

 was only his indomitable perseverance in the face of many 

 difficulties, if not actual opposition, which made success a 

 possibility. The catching and dissection of insects is a hobby 

 which even within walls devoted like our own to the further- 

 ance of science does not always secure unstinted praise, and 

 the catching and microscopic examination of mosquitos did 

 not meet with the approval of Ross's immediate superiors. 

 During the progress of his voluntary investigations he was for 

 a time sent to a station where he had no opportunity of study- 

 ing the subject. This fortunately was not until he had done 

 sufficient to attract the attention of the scientific world. 



Ross began his investigations by searching for the malarial 

 parasite in mosquitos. To this end he examined many hun- 

 dreds after they had fed on malarial blood. He found readily 

 enough that the flagella developed in their stomachs, but he 

 could not trace them further. By chance, however, he came 

 across a few dappled-winged mosquitos of a kind different 

 from those he had hitherto experimented with. Examining 

 these a few T days after they had fed on malarial blood, he 

 noticed something which he had found in none of the other 

 mosquitos. The walls of the stomach were studded with 

 peculiar little saccular bodies, which contained a pigment very 

 like that of the malarial parasite. These cells he noticed 

 were capable of growth, since they enlarged from day to day. 

 It was at this stage of his work that Ross was obliged to give 

 it up on account of his transfer to another station. He had, 

 however, created a good deal of interest in what he was doing ; 

 so much so that after a time he was relieved from military 

 duty and sent to Calcutta to continue his investigations. 

 Unfortunately, it was a time of year when little ague was to 

 be met with, and he had difficulty in getting material to 

 experiment with. In this dilemma he turned his attention to 

 a form of malaria in birds. He found that certain species of 

 mosquito fed on malarial sparrows showed growths in the 

 walls of their stomachs very similar to those we have men- 

 tioned ; but he went further. He bred young mosquitos from 

 the larvae, and when these were fed on malarial sparrows he 

 found these growths in a large percentage of them. Of those 

 fed on blood which was non-malarial none showed these 

 growths in their stomachs. He found, indeed, that the num- 

 ber of growths was roughly proportional to the number of 



