344 DISCUSSION. 



reported the presence of Agchylostomurn duodenale in the Islands in 1900. 

 At that time the species Necator americanus was not known, but the 

 anatomic description given of the parasite encountered here shows that 

 the species then described was not Necator americanus. 



< DISCUSSION ON THE PAPER, "MYZOMYIA ROSS1I AS A 

 MALARIA-CARRIER," BY DOCTOR VOGEL. 



Doctor Strong. — I am very much interested in the results of Doctor 

 VogePs experiments. About two years ago Mr. Banks, of the biological 

 laboratory, reported that Myzomyia ludlowii was capable of transmitting 

 malaria in the Philippines. We now know that this species is identical 

 with Myzomyia rossii. During the past year in connection with the 

 work in the courses of tropical medicine in the Philippine Medical School 

 relating to the study of malaria, we attempted to infect numerous speci- 

 mens of Myzomyia rossii by exposing patients suffering with severe cases 

 of sestivo-autumnal and tertian malaria to their bites. However, although 

 these experiments were extensive and were carried on over a period of 

 several months during the autumn, they were entirely unsuccessful. In 

 no case did the dissection of any of these mosquitoes, although a large 

 number were examined-, reveal any oocysts in the walls of the stomach, 

 and in the study of stained sections made of the salivary glands no sporo- 

 zoiites could be detected. Later attempts to infect other human beings 

 by the bites of specimens of Myzomyia rossii which had been previously 

 fed on the blood of patients suffering with severe malaria and whose blood 

 certainly contained gametes, also failed. The larvae of these mosquitoes 

 were collected in the estuaries about the city. 



In connection with Doctor Vogel's experiments the results we obtained 

 are interesting. We know that these estuaries are affected by the tides 

 and that more salt water would naturally enter them when the tides are 

 high and that after the season of the high tides has passed, more salt 

 would therefore be deposited in the marshes. In this way the breeding 

 places of these mosquitoes would at times contain a greater amount of 

 salt than at others. 



I do not recall at what time of the year Mr. Banks' experiments were 

 made. It would certainly be important to ascertain what effect, if any, 

 these changes in the character of the breeding places would have on the 

 transmission of malaria by Myzomyia rossii. 



Mr. Charles S. Banks, Biological laboratory , Bureau of Science, lecturer 

 on medical entomology, Department of Tropical Medicine, Philippine 

 Medical School, Manila, P. I. — The paper by Doctor Vogel is certainly 

 a very interesting one in that he has emphasized practically the same 

 conditions that I found at Olongapo, in my work upon the transmission 



