den wiederholt sich sehr viele Tage hindurch gegen Sonnenuntergang das Schauspiel 

 unzahliger Schaaren von A. claviger, welche die sich an den Thuren unterhaltenden 

 oder Abenbrod essenden Menschen angreifen. . . . Im Freien konnen die Anopheles 

 claviger, nachdem sie gestochen haben, auf die in der Nahe stehenden Baume flie- 

 gen und sich dort verstecken. . Die Miicken ruhen sich haufig auch auf den 

 ausseren Hauswanden aus und bleiben dort mehrere Stunden sitzen, am nachsten 

 Morgen aber sind sie nicht mehr verhanden. . . . Wir sehen sie die Beute in von 

 weniger oder mehr entfernten Orten her kommenden Schaaren anfallen. Im Allge- 

 meinen steht fest dasz sie durch jene Fenster und jene Thuren in die Hauser ein 

 fliege die nach der Richtung des Wassers liegen u. s. w." SAMBON (1901 p. 195) says 

 as follows : "During summer the A. maculipennis do not seem to remain long in the 

 houses and stables. Their number varies greatly from day to day in the same room. 

 Fresh specimens arrive every evening, gorge themselves on the blood . . . hide for 

 some hours in the darkest corner they can find and go out again in the morning 

 or the next evening". - 



At Maccarese GRASSI says that in July at 21 t. 30 he has hardly been able 

 to defend himself against A. maculipennis; this was the case whether he "was in the 

 house or out of doors. Also LEGER (1913 p. 41) records that he has caught A. m- 

 culipennis in many hundreds in the houses and on the railway stations in Corse. 

 With regard to tropical Anophelines DONITZ (1902 p. 20) says: "dasz die Tiere sich 

 sogar, nachdem sie sich mit Blut gesattigt haben, die Hauser welche ihnen nicht 

 zusagen verlassen um sich in Freien -zu verbergen. Already in Poland MARTINI 

 (1920 p. 61) indicates that at sunset A. maculipennis was flying as well in through 

 the windows as out of them. With these statements in mind the above-named diffe- 

 rences between PRELL'S and my views with regard to A. m. as a domesticated mos- 

 quito are intelligible. 



From these indications we now learn that A. maculipennis at all events round the 

 Mediterranean lives a life quite as we should expect the mosquito to live 

 if it were to be able to transfer malaria to man. At any rate it is here to 

 a rather high degree even nowadays an outdoor species which is on the wing to 

 find its prey over rather considerable distances, and to a very high degree it sucks 

 blood upon man. 



It is thus actually proved that there is the greatest difference in the manner 

 of life of A. maculipennis in South Europe and at the northern limits of its area 

 of distribution. In my opinion it is neither quininisation of mankind alone, nor 

 water drainage of the field, nor lowering of tp., but just this alteration in the 

 biology of the species, the very peculiar transition from an outdoor 

 species sucking upon man to a stable insect sucking upon our farm 

 animals which has been the main cau se of the disappearance of malaria 

 from its northern limits. 



The question now arises: what has caused this transition? I do not dare 

 to solve it for the niany foreign countries but I think I am able to do so for my 



