53 



ViALATTE (C.) & Parrot (L,.). Phl6botomes du Mslvoc—BuU. Soc. 

 Path. Exot., Paris, xiv, no. 9, 9th November 1921, p. 566. 



The species recorded from Morocco are Phlebotomus papatasii, 

 Scop., P. [Sergentomyia) perniciosus, Newst., P. (5.) sergenti, Parr., 

 and P. {Pro phlebotomus) minutus var. africanus, Newst. 



RouBAUD (E.). La DifE6renciation des Races zootropiques d'Anophfeles 

 et la Regression spontanee du Paludisme. — Bull. Soc. Path. Exot., 

 Paris, xiv, no. 9, 9th November 1921, pp. 577-595, 3 figs. 



Various criticisms of the author's theory on the relation of animals 

 and Anophelines in connection with the incidence of malaria [R. A.E., 

 B, viii, 141] are reviewed. 



The observations here described are to a large extent an answer to 

 these objections, and are concerned with the effect of the change of 

 food habits on the anatomy of the mosquito {Anopheles mactdipennis) . 

 The influence of natural selection on mosquitos that have adopted 

 domestic animals as their principal hosts has chiefly affected the mouth- 

 parts, and particularly the dentition of the saw-like edge of the maxilla. 

 In the normal mosquito, from a district where malaria is prevalent 

 and man is the usual host, the number of " teeth " averages about 13, 

 a number quite sufficient for the mosquito's needs. In districts where 

 cattle are plentiful and the mosquitos feed exclusively on them, an 

 average of 15 teeth is found, this being sufficient for feeding on 

 cattle if the proportion of available cattle is sufficiently high, as 

 compared with the number of mosquitos, to allow feeding to be easy 

 and undisturbed. In districts where this occurs, malaria is absent. 



But there are districts where cattle are present and the mosquitos 

 evidently prefer them, but where, under favourable conditions, a 

 certain amount of malaria also occurs. The reason for this is that the 

 proportion of mosquitos as compared with the available cattle is so 

 high that the former are sometimes (though unwillingly) compelled to 

 feed upon man. 



In such districts, owing to the greater difficulty of obtaining blood 

 from cattle, specialisation in the mosquitos has been continued to a 

 higher degree, as many as 18 teeth being found on the maxilla. The 

 great benefit that the mosquito derives from a larger number of teeth 

 in obtaining food from cattle, is shown by the fact that, in a large 

 number of mosquitos captured in a certain district, the average number 

 of teeth in freshly emerged specimens was 14-3, whereas the average 

 number of teeth in gorged specimens was 16-6. 



The author suggests that an examination of the number of teeth in 

 the mosquitos of a given district will indicate the liability to malaria 

 of that district. Wliere the teeth are very few the district is, of course, 

 a malarious one, where, on the other hand, they are very numerous, 

 the mosquitos, though they feed on cattle as their normal host, may 

 by the severity of competition at any time be forced to feed upon 

 man, and thus may give rise to a certain amount of malaria. 



Wesenberg-Lund considered that the adaptation of mosquitos to 

 cattle was a characteristic that they quickly acquired, as in Denmark 

 malaria has only comparatively recently disappeared [R.A.E., B, ix, 

 153]. The author, however, considers that this characteristic was only 

 acquired over a considerable period of time, and explains the rapid 

 disappearance of malaria by assuming that the mosquitos had already 

 acq,uired a liking for cattle, but that the cattle were not available in 



