127 



In summary, laboratory experiments can only prove the suscepti- 

 bility of a species of mosquito to malaria under more or less artificial 

 conditions and, in a large series, the approximate degree of suscepti- 

 bility. However, judging from the agreement of laboratory experi- 

 ments 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 makes it probable that some species of 

 Anopheles may be readily infected with malaria parasites, but offer 

 comparatively unfavourable conditions for their development. 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. 



In experiments to test the infection of man with malaria by means 

 of Anopheles rossi there were unfortunately no infected A. rossi 

 available of which the larvae had been examined, so that we lack 

 the crucial test as to which type was used for infecting the experimental 

 cases. However, the evidence points very strongly to the typical 

 form being the one concerned. 



The results are shown in tables. The evidence seems clear that 

 these experimental cases were infected with malaria as the result 

 of exposure to A. rossi infected in the laboratory. The possibility 

 of a relapse from a former infection must be always taken into account 

 in such experiments when performed in a malarious country. But 

 that such relapses should follow exposure to infected mosquitos in 

 two cases, one occurring fourteen and the other seventeen days after 

 exposure, would be a remarkable coincidence indeed, especially, in 

 view of the fact that both patients experimented upon had been known 

 to be free from fever many days before the tests and that both showed 

 the same type of parasite as that which infected the mosquitos. 



It also seems clear that a single individual of A. rossi may infect 

 at one exposure. The fact that the case that received sporozoites 

 from two infected mosquitos, and, presumably, the larger dose, 

 showed an earlier appearance of parasites and the more marked 

 symptoms may be only a coincidence, but it is worthy of note. One 

 can do httle more than guess at the number of sporozoites injected 

 by a single mosquito, but judging from the number of sporozoites 

 found at dissection after feeding on the experimental cases and 

 comparing with the numbers observed in the salivary glands of many 

 infected mosquitos of the same species, one would say that the effective 

 number is a matter of hundreds rather than of thousands, and more 

 probably a matter of scores. 



These experimental cases serve well to show the great variety of 

 manifestations observable in subtertian malaria. 



Interim Report of the War Office Committee for the Study of Trench 

 Fever. — JZ. R.A.M.C, London, xxx, no. 3, March 1918, 

 pp. 351-353. 



This paper records experiments undertaken by the War Office 

 Committee for the purpose of determiDing the role of the louse in the 



