282 DE VOGEL. 



chloride and also from fresh water, sucked the blood later than those 

 from water with 1.3 per cent. 



A gradual decrease was observed in the number of gametes in the 

 peripheral blood during the time the patient was in the hospital, and 

 this was strikingly apparent during the last days of her stay. During 

 the first days, gametes were found in every field, and in the fresh blood 

 the microgametes were seen repeatedly, swarming out of the microgame- 

 toeytes. When the patient left on November 13, only a few crescents 

 were discovered in the preparation after considerable search. On ex- 

 amining the fresh blood in the last days, many phagocytes were seen 

 actively employed in absorbing the crescents, a clear proof of the way in 

 which the human organism rids itself of this infection. 



The diminished chances of infection when a much smaller number of 

 gametes are present than there were originally, is an important' factor, 

 which must certainly not be neglected in considering the negative results 

 of the last days of the experiment, when, as it happened, mosquitoes 

 from water with a low or hardly any percentage of salt were tested. 



Although, of course this inquiry in no way lays claim to completeness, 

 yet where the chances of carrying out the experiments are so rare it 

 seemed to me not out of place to publish the result, as at least it has 

 been shown experimentally that Myzomyia rossii can be infected with 

 Plasmodium immaculatum. This fact alone seems to me of no little 

 importance, as, among other things, it clearly shows the way in which 

 malaria may spread along the coast in our Indian islands. In order to 

 be certain that the mosquitoes which I used in these experiments really 

 were M. rossii. I sent the specimens of the same breed which we had kept 

 for determination, to Professor Nuttall, of Cambridge, with the request 

 that they might also be submitted to Theobald. I take this opportunity 

 of expressing my sincere thanks to Prof essor Nuttall for the way in which, 

 with his usual obliging kindness, he complied with my request. 



All the specimens obtained from larva? collected on six different dates 

 from six different breeding places proved to be Myzomyia rossii. What 

 remained of the mosquitoes 2, 3 and 5, after dissection, namely, the wings, 

 legs, head with thorax and abdomen, was also sent in 'three separate tubes 

 filled with alcohol and marked 2, 4 and 5. I was informed that Theobald 

 said he was unable to effect a determination from the fragments sent to 

 him. The chance that just these specimens should happen to belong to 

 another species is too slight to be considered. 



Although these experiments, made with the purpose of infecting 

 Myzomyia rossii taken from water containing 1.3 per cent sodium chloride, 

 may not in themselves lead to any definite conclusion, as to the positive 

 influence of the salt contained in the breeding places upon the liability 

 to malarial infection of Myzomyia rossii developed in such a solution, 

 nevertheless the hypothesis that such an influence exists is supported by 



