32 The Philippine Journal of Science i9is 



Table XVI. — Positive and negative Anopheles in four collections. 



Col- 



i lection 

 ■ No. 



Positive. 



Negative. 



1 

 2 

 3 



4 





46 A. umbrosus. 



7 A. umbrosus, 1 A. rossi, 1 A. ludlowi, 



2 A. barbirostris, 1 A. sinensis, 1 A. tessel- 



latus. 

 2 A. ludlowi, 2 A. umbrosus, 5 A. ros»i. 











Of the 8 positives of different species ova were well developed 

 in 5. In nearly every case where a positive was obtained the 

 average percentage of well-developed ova in both positive and 

 negative dissections was high. 



SUMMARY BY SPECIES 



Anopheles ludlowi. — Much evidence has been adduced by 

 Christophers and others that indicates that ludlowi is an im- 

 portant carrier of malaria in certain coast regions. The high 

 percentage of infections with ready formation of sporozoites 

 observed in the experimental series described in this paper, as 

 well as the finding of a naturally infected specimen with sporo- 

 zoites in the salivary glands, would go to confirm the evidence 

 already obtained regarding the dangerous character of this 

 species. 



Anopheles rossi. — The comparatively high percentage of in- 

 fections observed by me in the brackish water type of var. 

 indefinitus would bring this form under suspicion, although spo- 

 rozoites are apparently not readily formed. Epidemiological 

 evidence in the coast regions of the Federated Malay States is 

 at fault, since this type of rossi is there so commonly associated 

 with ludlowi and umbrosus, both known carriers. 



The var. indefinitus collected in fresh water shows a low degree 

 of susceptibility to experimental infection and but little tendency 

 to formation of sporozoites. Neither experimental nor epide- 

 miological evidence indicates that this species is an important 

 carrier. 



An-ophcles rossi type Giles of Malaya shows a comparatively 

 high percentage of infections in laboratory experiments, and 

 sporozoites are readily formed. Further, as shown in the second 

 part of this paper, this type is capable of infecting man under 

 experimental conditions. Epidemiological evidence from other 

 countries, India in particular, indicates that A. rossi Giles is 

 rarely, if ever, a transmitter of malaria. But, as stated in the 



