181 



Lang (1920 p. 75). Prell (1917 p. 244). Vogel (1917 p. 1509) and hereto may also 

 be added some remarks by Muhlens with regard to the malaria outbreak in Wilhelms- 

 hafen (1909 p. 1(59); Martini (1920). 



Curiously enough in the great work: Studies in Relation to Malaria, the authors 

 of the first part (Nuttall, Cohbelt and Strangeway-Pigg) seem to show that they 

 have never any idea of the occurrence of .4. maculipennis in stables. 



It will now firstly be understood that the main results of my own observations, 

 that the Anophelines do not attack man, that they suck blood upon our domestic 

 animals, and that they show a remarkable predilection for stables in comparison with 

 our dwelling rooms have all almost simultaneously been corroborated by a 

 great many observers; about the correctness of the observations there can now 

 be no doubt. It may be regarded as a matter of fact that, what I thought had validity 

 only for Denmark, is really valid for almost the whole of Central Europe, Great 

 Britain, and for some few areas to the south of the Alps (Toscana). To me how- 

 ever it is rather a remarkable circumstance that of these many foreign observers 

 all unknown to me, who have almost in some measure made my now published 

 investigations superfluous, and among whom many understand that all the old ex- 

 planations of the fact that malaria has receded from such vast areas of its former 

 territories, are insufficient, no one, as far as I know, have understood what, in my 

 opinion, must necessarily be inferred from all these investigations. 



For it can now be proved that, over the vast area — more than half of Eu- 

 rope — where formerly A. maculipennis brought down disease and often death on 

 mankind, the peculiar phenomenon now prevails of an Anophelism without malaria, 

 already known as a remarkable exception in one of the fatherlands of malaria in 

 Europe. From these many investigations, carried on independently by each inves- 

 tigator without any knowledge of the researches of the other workers in the same 

 field, we are now able to show that the real cause why malaria has receded from 

 the greater part of Europe is that .4. maculipennis has lost its co nnecti on with 

 man. If nowadays after the war no outbreak appears North of the Alps, 

 this must in my opinion partly be referred to this fact. 



Secondly it must be understood that over vast parts of distribu- 

 tion a change has taken place in the habits and biology of the mos- 

 quito within the last century. That this has been the case can in fact 

 be shown. 



Apriori it may be regarded as a matter of fact that when the Anophelines 

 even nowadays in South Europe especially in the Balkans, but also in Italy, yearly 

 transfers malaria to hundreds of thousands of people, it cannot live its life 

 there as it nowadays does in more northern latitudes. In his excellent 

 work Grassi has elaborated the biology of .4. maculipennis in an admirable man- 

 ner: "He writes (p. 58) that during the summer months numerous specimens of .4. 

 maculipennis remain outdoors in Nature, p. 105 he further writes: "Die A. chwiger stecken 

 sowohl im Freien wie in den Hausern und in den Stallen. In den Malariagegen- 



