204 MOSQUITOES OF NORTH AMERICA 



Kiuoshita states further that Anopheles listoni does not occur in Japan and 

 that the country has always been free from pernicious malaria in spite of the 

 fact that persons suffering with pernicious malaria frequently come to Japan. 

 On the other hand, Kinoshita found that both in Formosa and Japan Anopheles 

 sinensis is the principal transmitter of tertian malaria. By experimentation 

 he found that about 50 per cent of this species became infected with tertian 

 parasites; quartan parasites developed in this mosquito only at low tempera- 

 tures and the parasites of pernicious malaria never. Another interesting point 

 in this connection is that he not rarely found new infections of tertian malaria 

 in winter, while this was not the case with pernicious malaria. The explanation, 

 lies in the fact that in Formosa Anopheles sinensis is active throughout the 

 winter. 



It will thus be seen that negative results with a given species of Anopheles 

 are not conclusive unless the experiments are conducted with all types of malaria 

 and under the most favorable conditions. Furthermore it would appear that 

 different species of Anopheles, where susceptible to the same types of malaria, 

 may be so in different degrees. Grassi, Bignami and Bastianelli, in their early 

 experiments, had found that a certain proportion of the Anopheles appeared to 

 be naturally immune and failed to develop the malaria parasite, even under the 

 most favorable conditions. This proved to be the case with all the species of 

 Anopheles and of parasites experimented upon by them. 



In a recent paper Dr. Samuel T. Darling discusses the relation of the various 

 species of Anopheles to malaria in the Panama Canal Zone. His careful studies 

 show that Anopheles alhimanus is the principal transmitter of malaria, both 

 a3stivo-autumnal and tertian, in that region. He found that 70.8 per cent of 

 the individuals of this species which he induced to bite malarial patients became 

 infected. He also found that this was the species which frequented houses most, 

 constituting in Ancon, during October, 1908, 73.5 per cent of the Anopheles 

 found, and in some villages being the only species present. Of Anopheles 

 pseudopunctipennis it was found that 12.9 per cent of the individuals experi- 

 mented with became infected, while of 17 A. malefactor none became infected. 

 Anopheles argyritarsis and A. tarsiniacuJaia were later found by him to be 

 malaria transmitters. 



The brothers Sergent have recently found sporozoits, probably malarial, in 

 the salivary glands of Anopheles algeriensis and A. hispaniola in Algeria. In 

 addition to the malaria-bearing forms above mentioned, Theobald in the fourth 

 volume of his monograph lists Anopheles harhirostris, A. pseudopictus and A. 

 theoialdi as transmitters of the malarial parasites. 



THE HABITS OF ANOPHELES MOSQUITOES. 



The general points of difference between adults of this group and those of 

 other mosquitoes are very well understood, the long palpi of the female as con- 

 trasted with the short palpi of the females of most other mosquitoes, for example. 

 The other points of difference will appear from the systematic descriptions. 



