﻿LITTERATUR 



259 



Arbetet avslutas med en \tterst utförlig och kanske onödigt brett 

 lagd men särdeles intressant Iramställning av Anop/ie/cs-antimx särskilt 

 A. inaculipeiDiis^ och deras lörhällande till tVossan. VVesenuerg-Lund 

 påvisar, att i Danmark, säväl som i en del andra nordliga lander, A. ma- 

 cuUpennis tillbrmgar hela sommaren i ladugårdar, endast dä oci'i då fly- 

 gande ut iör parning och äggläggning. Vintern tillbringas i ouppvärmda 

 uthus. Människan antalles 1 regel ej, utan myggan lever av husdjurens, 

 speciellt kors och svins, blod. Endast pä vissa trakter, som genom vat- 

 tenrikedom utgöra gynnsamma kläckningsplatser, men där samtidigt fö«^a 

 boskap hålles, såsom t. ex. omkring Silkeborg, angripes människan. 



Som bekant har frossan, eller som vi med tanke på dess häftighet 

 gott kunna kalla den, malarian, tidigare härjat fruktansvärt i Danmark. 

 1826 utbröt den första starka epidemien; 1831 — 34 förekom även en be- 

 tydande sådan. Senare hava blott smärre epidemier konstaterats (1847 — 

 49, 1853—56, 1859—62), varefter sjukdomen märkbart avtagit. Följande 

 intressanta, från C. A. Hansen hämtade beskrivning över förloppet av 

 183 1 — 34 års farsot tillåter jag mig här anföra: »After a few days of a 

 nasty smelling blighting fog in July the malaria suddenly attacked a very 

 great part of the population. As by a flash of lightning several hundred's 

 were attacked in all directions in the same parish. Upon Lolland there 

 were two parishes with 2 000 inhabitants of which i 800 were attacked 

 and 98 died. The percentage of mortalitv was greater in the Cholera 

 year 1853 when more than 50 % of the attacked succumbed, but the 

 actuel number of attacked persons was much greater in the malaria 

 years». 



Wesexberg-Lund kommer härefter in på de olika teorier, som fram- 

 ställts till förklaring av frossans avtagande, samt kommer till det resulta- 

 tet, att ingen är fullt tillfredsställande. På grund av andras och egna 

 undersökningar sammanfattar han sin egen mening på följande sätt: 

 » — — we are now able to show that the real cause why malaria has 

 receded from the greater part of Europe is that A. macidipennis has 

 lost its connection with man». — »Secondly it must be understood that 

 over vast parts of distribution a change has taken place in the habits and 

 biology of the mosquito within the last century. That this has been the 

 case can in fact be shov/n.» — »Apriori it may be regarded as a matter 

 of fact that when tlie Anophelines even nowadays in South Europe 

 especially in the Balkans, but also in Italy, yearly transfers malaria to 

 hundreds of thousands of people, it catinot live its life there as it now- 

 adays does in 7nore iwrtJiern latitudes.» »It is thus actually proved 

 that there is the greatest difference in the manner of life of A. 7nacuU- 

 pennis in South Europe and at the northern limits of its area of distribu- 

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

 water drainage of the field, nor lowering of tp., but jicst t/iis alteration 

 in the biology of the species, the very peculiar transitioii from an outdoor 

 species sucking upon matt to a stable insect sucking upon our farm ani- 

 mals which has been the ntai?t cause of the disappearance of malaria 

 from its fwrthern limits. •••> — »The question now msQS: what has caused 

 this tratisition .~ I do not dare to solve it for the many foreign countries 

 but I think I am able to do so for my own country.» — »It is a well 

 known fact that in the eighteenth century, and still in the first quarter 

 of the nineteenth, the swine were driven to the woods where they lived 

 on mast; special swine stables were hardly known. Horses and cattle 

 lived the greater part of the year out of doors, — — » — »It will be 

 clearly understood that this change in Danish agriculture must of course 

 be of the greatest significance to the Anophelines; for duri?ig a great 

 part of their flying time the large mammalia year after year disap- 

 peared from their flying areas. t> 



Teorien synes kanske något djärv, lösryckt ur sitt sammanhang, som 



