XIII, B, 1 



Barber: The Transmission of Malaria 



13 



per hundred leucocytes at least. Nearly all of the carriers, 

 including those who failed to infect mosquitoes, had a much 

 higher percentage of gametes than 1 per cent. In many cases, 

 no doubt, it was more or less a matter of chance that no infec- 

 tions occurred, but that there is a difference in carriers aside 

 from the number of gametes harbored in the blood, and that 

 the same carrier may vary at different times, will be shown in 

 connection with later tables, especially Tables X and XI. In 

 a considerable percentage of the noncontrolled cages the carrier 

 at some previous feeding had infected some of the mosquitoes 

 exposed. 



In Table IV are given the percentages of infection of the 

 mid-gut in both controlled and noncontrolled cages. These per- 

 centages are of little value in comparison of species where num- 

 bers are small, since chance plays a large part in the result, but 

 where numbers are large, the table may be of use in indicating 

 in a general way the probability that mosquitoes of a given 

 species may. become infected through biting one or more of a 

 miscellaneous lot of carriers such as might be found in a ma- 

 larious community. 



Table IV. — Controlled and noncontrolled cages by species. 



Species of Anopheles. 



A. ludloivi 



Var. indefinitus, brackish water 



Var. indefinitus, "known" 



Var. indefinitus, "probable" 



Type Giles, "known" 



Type Giles, ' 'probable' ' 



Type Giles, indefinitus mixed 



A. kochi 



A. 

 A. 

 A. 

 A. 

 A. 

 A. 

 A. 

 A. 

 A. 



aconitus 



fuliginosus . 

 maculatus . 

 kawari 



umbrosus __ 



hunteri 



barbirostris- 



smensis- 



aitkeni.. 

 Total 



Dis- 

 sected. 



Positive. 





Per cent. 



96 



43.4 



344 



9.0 



165 



4.8 



73 



2.7 



175 



21.1 



306 



14.7 



245 



10.2 



31 



29.0 



22 



18.2 



33 



9.1 



40 



17.5 



31 



32.3 



240 



10.4 



10 



10.0 



197 



1.5 



64 



1.6 



1 



0.0 



2,072 



12.2 



In Table V dissections are classified according to the type of 

 gamete harbored by the carrier. Controlled series alone are 

 included. 



