153 



At the i)rescnt time there is a general emigration of men and cattle 

 in the hot season, especially from the east coast of Corsica, to the hills. 

 The result is tliat during the period when Anophelines reach their 

 maximum numbers there remain in the plain only a few small agri- 

 culturists, indispensable railway officials, etc., in the presence of an 

 excessive and very hungry Anophelinc population that finds no other 

 host. The danger to man is obvious. It is hoped, however, that if 

 considerable improvements are made in the conditions of life on the 

 plain, by better water supply, quinine prophylaxis, antilarval measures 

 and suitable stabling for animals, it may be possible to retain both 

 agriculturists and their cattle there during the hot season. The 

 task is a heavy one, but the future development, even the life itself 

 of Corsica, depends upon its execution. 



Wesent!Erg-Luxd (C). Sur les Causes du Changement intervenu dans 

 le Mode de Nourriture de I Anop/iclcs )ii(iculipcnnis. — C.R. Soc. 

 Biol., Paris, Ixxxv, no. 26, 16th July 1921, pp. 383-386. 



In this paper the author amplifies his theory regarding the change 

 of habits of Anopheles macttlipennis in Denmark and the consequent 

 disappearance of malaria from that country [R. A.E., B. ix, 83]. He 

 considers that, besides the change in agricultural practices, the geo- 

 graphical situation of the country has also had some bearing on the 

 phenomenon, Denm.ark being the extreme northern limit of the species. 

 It is a noticeable fact that the change remarked in Denmark may also 

 be traced in other regions of Europe where malaria has previously 

 been prevalent and has now almost entirely disappeared. This is 

 particularly true of the countries north of the Alps, where, by 

 reason of easy conditions of life and abundant nourishment in cattle 

 sheds, A. maculipcnnis is found to have appreciably increased in 

 size, while south of the Alps, where it is always the chief malaria-carrier, 

 the domestic animals spend the greater part of the year entirely out of 

 doors. A hypothesis that appears probable to the author, but which 

 requires further research in Germany for its verification, is that the 

 Anopheles that now attack man are those that have over-wintered, 

 while the summer generations feed only on the blood of animals. This 

 would explain the curves of malaria incidence which, towards the north, 

 do not generally show two maximum heights, but only one, which falls 

 in May. Much still remains to be discovered on this subject ; in par- 

 ticular, information is desirable on the life of the malarial parasites 

 during the periods when epidemics remain stationary. 



The author again calls attention to the work of Roubaud [R. A.E., 

 D, viii, 141], according to whom the changes in the life of A. mactdi- 

 pennis are the results of a slow and steady evolution in the feeding 

 habits of the Anophehne. The author views them, however, as a 

 phenomenon that has appeared with almost incredible rapidity. He 

 believes that A. maculipennis, as living north of the Alps, does not 

 represent a distinct subspecies or local race, but is simply a con- 

 tingent of individuals developing physical and physiological features 

 other than those that usually characterise their species. For the 

 moment, the bond between Anopheline and man is broken in the 

 latitude in question, but the cycle might be resumed at any time, 

 though as a matter of fact the renewal of great malarial epidemics 

 is a most unlikely occurrence. 



(4U57) M 



