xm, b, i Barber: The Transmission of Malaria 35 



ditions were also negative. Anopheles tessellatus was found 

 abundantly on one occasion, both in jungle and in pools more 

 or less exposed to the sun, but there was no opportunity of test- 

 ing them on a carrier at that time. Of a small lot of larvae 

 obtained later, only two adult females were obtained, and both 

 failed to take blood. 



In summary, laboratory experiments can only prove the sus- 

 ceptibility of a species of mosquito to malaria under more or 

 less artificial conditions and, in a large series, the approximate 

 degree of susceptibility. However, judging from the agreement 

 of laboratory experiments with other evidence in the case of 

 known carriers, it may be concluded that a high percentage of 

 infections experimentally with the formation of sporozoites in 

 the salivary glands furnishes strong presumptive evidence 

 against a given species. The evidence adduced in connection 

 with A. rossi (Table XIV) makes it probable that some species 

 of Anopheles may be readily infected with malaria parasites, 

 but offer comparatively unfavorable conditions for their develop- 

 ment. On the whole, the experiments included in this paper 

 make it doubtful whether any common species of Anopheles in 

 Malaya, with the possible exception of two or three jungle 

 forms, is immune to infection and can be wholly acquitted of 

 carrying malaria under certain conditions. 



TECHNIC 



No attempt is here made to describe the entire technic em- 

 ployed in this work, but it may be worth while to mention a 

 few modifications of the usual technic that have proved es- 

 pecially serviceable. 



Where many larvae have to be examined, I have found a spe- 

 cial kind of slide very convenient. Four small pieces of cork 

 or thick cover glass are cemented to an ordinary slide in such 

 a position as to support a cover glass, say 3/4-inch square, at 

 the corners. These cork supports are made of such a height 

 that a larva placed under the cover is held, but not crushed. 

 As larvae vary somewhat in size, it is well to have two or three 

 sorts of slides at hand. These are best made in duplicate, in 

 order that one may examine one or two larvae on one slide, while 

 an assistant is placing other larvae on a second. It is convenient 

 to have a cover glass that projects a little over the slide, so 

 that it is easily caught in the fingers in transferring it to another 

 slide. I have examined many hundreds of larvae in this way, 

 and I find that one can work very rapidly by this method 

 and, judging from the subsequent development of the larvae, 



