199 



Grassi (B.). Osservazioni suUa Vita degli Anofeli. [Observations on 

 the Life of Anophelmes.\— Rend. R. Accad. Naz. Lined, Rome, 

 Classe Sci. fisiche, matemat. e naturali, xxix, nos. 10-11, 21st 

 November-5th December 1920, pp. 307-313, 339-344. 



During the summer of 1920 fourteen batches of about 10,000 marked 

 AnopheHnes were released in a locahty where mosquitos find httle 

 shelter, so that the conditions for recapture were most favourable. 

 In spite of dihgent efforts, only 1 -8 per cent, were retaken, and hardly 

 any after 12-14 da vs. The author concludes that in the warm season 

 the life of xAnophelines is very brief. This is supported by the obser- 

 vation that most infected Anophelines harbour zygotes in early stages 

 of development, and as a rule the Anopheline host perishes before 

 the zygote matures. Sella has observed that in warm weather the 

 development of each batch of eggs only requires 2-4 days, so that the 

 mosquitos would increase enormously were it not for the high mortahty. 

 Roubaud and Griffith ascribed the disappearance of marked specimens 

 to migration, but the conditions attending the author's experiments 

 point to a high death-rate being the probable explanation. 



This mortality of Anophelines may help to explain their presence 

 in the absence of malaria, for of a hundred specimens that have fed 

 perhaps only one lives for the period of 13-15 days necessary for the 

 sporozoits to reach the salivary glands and to transmit infection. 

 This also explains why the return of malaria-infected troops only 

 causes a temporary increase of malaria in places that are not decidedly 

 mosquito-infested. 



AnopheHnes, while the\- frequently go away from the locality where 

 they have fed, tend to return there. This tendency to return is 

 hmited, but suggests measures against the adults in dwellings — 

 particularly where cases of malaria exist — rather than in pigsties, etc. 



Grassi (B.). L'Anofele pud propagare la Malaria direttamerite ? 



[Can Anopheles also transmit Malaria chrectly ?] — Reud. R. 

 Accad. Naz. Lincei, Rome, Classe Sci. lisiche, matemat. e naturah, 

 XXX, no. 11, 3rd June 1921, pp. 336-337. 



Experiments are described which appear to prove that the author's 

 hypothesis that malaria may be directly transmitted [R.A.E., B, 

 ix, 142] has no foundation. 



Grassi (B.). L'Anofele pu6 propagare la Malaria direttamente ? 



[Can Anopheles also transmit Malaria directly?] — Atti R. Accad. 

 Naz. dei Lincei, Rome, xxx, August 1921. (Abstract in Ann. 

 d'Igiene, Rome, xxxi, no. 9, September 1921, pp. 582-583.) 



Continuing the experiments referred to in the preceding paper, 

 further work has been carried out with the same negative result. 



The saliva of Cnlex kills the human malarial parasite, while that of 

 Anopheles does not do so. Furthermore it is known that an Anopheline 

 driven away before it is satisfied may immediately bite anew, and 

 there might be a possibility of the new host being infested by a regur- 

 gitation of infected blood" previously obtained. Hence the need for 

 these experiments. 



