152 



owing to its more rapid development in the mosquito, will later on 

 mask at first the manifestations of the aestivo-autumnal parasite, 

 inoculated later. This theory explains, at least in part, the curious 

 facts of succession of the seasonal epidemiology of the two parasites, 

 without recourse to the hypothesis of problematical and inexplicable 

 change advanced by the partisans of the unicist theory. Doubtless 

 the direct action of" climate has some influence also on the seasonal 

 appearance of the various species of Plasmodium in the blood. 



A study of the relations of Anophelines to farm animals and poultry 

 in Corsica is of particular interest for the purpose of comparison with 

 observations in those parts of the Continent where the same species 

 ( .4. maculipennis) occurs, as in la Vendee, where it appears in no less 

 numbers, although malarial infection is very much less [R.A.E., B, 

 viii, 141]'. In the most heavily infected parts of Corsica, such as the 

 eastern coast, domestic animals are present in considerable numbers, 

 at least until the summer emigration of the herds to the hills. In all 

 the locahties visited by the authors, however, in spite of the most 

 thorough examinations of the buildings occupied by animals, Anophe- 

 lines were practicallv never found there, although in human habitations 

 they were nearly always present. In Corsica 80 per cent, of the Anophe- 

 lines taken in "houses were gorged with blood, while in the Vendee 

 region the percentage was only 14. The conclusion has been reached, 

 after careful observations, that A. maculipennis is as much attracted 

 to cattle in Corsica as on the Continent, but that the type of building 

 used for sheltering animals is totally unattractive to the mosquito. 

 The stables and sheds are frequently open to the air, or have holes 

 in the roofs where the wind and sun can penetrate ; others are too 

 large and have very high ceilings. This confirms Wesenberg-Lund's 

 theory, that in Denmark the disappearance of malaria coincides with 

 agricultural development and with the perfecting of the stabling of 

 animals that previously had only primitive or no shelter for the 

 night [R.A.E., B, ix, 82]. 



Prophylaxis against malaria is progressing satisfactorily in Corsica, 

 but is not sufficient without other protective measures. Anti-larval 

 measures have scarcely been begun, and require much more serious 

 attention. The recent" introduction of trioxymethylene powder as an 

 efficient larvicide should much facihtate control on the large stretches 

 of marshy ground. Drainage is an important question. Animal 

 prophylaxis seems to be one of the principal means of ridding human 

 habitations of the mosquito pest ; it is absolutely necessary for this 

 that the animals should be sheltered in permanent stables, at least 

 after sundown, the buildings being not too high and properly built. 

 Simple shelters made of branches or pressed earth and covered with 

 a thatch are quite sufficient, but the tops of these must be thoroughly 

 closed in and protected by a strong roof and sides ; small, low shelters 

 are much preferable to the high buildings so common in Corsica ; the 

 height should not be more than 11 ft. 6 in. from the ground. The 

 chief objection to such buildings is that cattle would feel the heat 

 too much in the hot season ; to obviate this, the lower part could be 

 made easily removable ; the essential is that, about halfway up, the 

 walls should become so thick and dark that the Anopheline, im- 

 mediately after having fed, would find suitable shelter. The con- 

 struction of rabbit hutches should follow the same plan. Poultry are 

 useless in this respect, as A. maculipennis only very exceptionally 

 attacks them. 



