DISCUSSION. 345 



of malaria by Myzomyia rossii. 1 I might also say that in the Province 

 of Lepanto-Bontoc, where the town of Cervantes is situated, many 

 miles from any possibility of salt-water influence, I found this mosquito 

 breeding in sluggish streams of purely fresh water. The parasite was 

 found in great abundance in the blood of the natives at this latter 

 place. I may state, in referring to the question of the saltness of the 

 water, that I did my first work at Olongapo, where I bred this mosquito. 

 Topographically, Olongapo is like Manila, except that the ramifications 

 of the land are not so extensive and all the estuaries in the vicinity are 

 affected by the water of Subig Bay, which is as salty as that of Manila 

 Bay and the China Sea. 



I doubt very much if the mosquito in Manila could be said to breed 

 in water which is not salt. As far as I have found, this mosquito is 

 prevalent only in the estuaries of Manila that are distinctly affected by 

 risinsr tides. 



DISCUSSION ON THE PAPER "ANTIMALARIAL PROPHY- 

 LACTIC MEASURES AND THEIR RESULTS AT THE 

 NAVAL STATION, OLONGAPO, P. I.," BY 

 DOCTOR DUNBAR. 



Mr. Banks. — The observations of Doctor Dunbar are identical with 

 my own at Olongapo. It was certainly true that the largest percentage 

 of Marines who had malaria had been sent to the navy rifle range for target 

 practice and were therefore in a region abounding in malaria. As Doctor 

 Dunbar says, there was a great increase in malarial infection as the dry 

 season advanced. 



I have a map, which anyone may see who wishes to, which shows the 

 topography of Olongapo and also the location of the mosquitoes as I found 

 them. The point regarding the inadequacy of mosquito nets was also 

 brought out by me in my paper. The different seasons of the year strongly 

 influence the abundance of the mosquitoes. It is a well-known fact that 

 they can not exist during the rainy season. The hard rains destroy them, 

 as the larva? remain on the surface of the water. During the dry season 

 there is. no such menace to their existence. 



Doctor Highet. — I should like to refer to two interesting measures on 

 antimalarial work which were carried out in Siam, one of which was of 

 special interest. 



The first experiment was performed on the old quarantine station of 

 Bangkok, situated on the Island of Koh Phai, in the Gulf of Siam, 

 and some few miles from the mainland. There Anopheles mosquitoes 

 abounded and malaria was of a very severe type, but after carrying out 



1 This Journal, Sec. B (1908), 3, 335. 

 96475 7 



