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increase in the Anoj)heline population requiring greater nourishment. 

 This has been known to occur in la Vendee. The immigration of 

 small settlements of people with but few cattle in a marshy zone 

 previously uninhabited may give rise to the outbreak of fresh malaria 

 epidemics. This explains the occurrence, during the War, of several 

 small foci of indigenous malaria reported from districts poor in cattle. 

 The spontaneous decrease in malaria, so noticeable in the lowlands of 

 la Vendee, in Flanders and Holland, and in the swamps of Tuscany, is 

 coincident with the reclamation of these swampy areas and also with 

 an alteration in the habits of the Anophelines owing to animals having 

 been substituted for man as hosts. This seems to have been a slowly- 

 acquired habit ; the repugnance for human blood is certainly not 

 primitive, all that is known of the malaria cycle points the other way, 

 and in essentially malarial countries, such as the unhealthy parts of 

 Italy described by Grassi, the eastern coast of Corsica, Algeria, 

 Morocco, the East, etc., A. maculipennis, far from avoiding man, may 

 be found engorged with blood in the majority of houses and encamp- 

 ments. The secondary adaptation of this species to animals in 

 countries where domestic cattle are abundant seems to have produced 

 a particular race of mosquito, which is distinguished not only by its 

 tastes and affinities, but also by its greater size. In modifying their 

 primitive habits of nutrition at the expense of man, the Anophelines 

 of the cattle-stocked regions have broken the closed cycle followed 

 hitherto by the malaria parasites, and suspended the endemic 

 manifestations of the disease. 



The author beheves that there is an interesting possibihty of 

 introducing what he calls animal prophylaxis in malaria, that is, the 

 importation of cattle to act as a protection to man, and this should 

 be particularly successful in places where the development of the 

 Anophehne fauna occurs in isolated breeding-places. The cattle 

 stables might be used as traps, and if thorough and extensive destruction 

 of the mosquitos were regularly practised during the period preceding 

 the outbreak of malarial epidemics, the efficiency of the animal 

 prophylaxis should be brought to its maximum. The biological 

 necessities of other species than A. maculijpennis would also have to be 

 considered. It must be remembered also that the introduction of 

 animal hosts is not by itself sufficient as an anti-malarial measure ; 

 the necessary conditions of stabhng, etc., must also be compHed with, 

 and these will vary according to the species. For the purpose of 

 considering this prophylaxis, the author divides Anophehnes into 

 two main groups, viz., entophilous species hke A. maculipennis, that 

 seek their hosts in rooms or closed buildings, stables, etc., and 

 exophilous species hke A. bifurcatus, that attack their hosts in the 

 open air or under verandahs, sheds, etc. A third group might be 

 called amphophilous, and would consist of those species that attack 

 equally in or out of doors. The cattle used as protection would 

 therefore have to be placed under conditions of attack corresponding 

 to the different biological categories, the local methods of rearing cattle 

 being modified more or less completely to suit the requirements of the 

 human population. When the necessary local modifications are 

 understood, it is believed that this new prophylactic measure would 

 contiibute largely to the elimination of malaria. 



