163 



I saw that \ve have arrived at quite the same results. I do not think that the 

 excellent paper of ROUBAUD has made mine superfluous; the same theory which 

 already in 1918 I had worked out for myself with regard to the disappearance of 

 the malaria in North-Europe I have seen that ROUBAUD has also worked out for 

 France. His thoughts and mine upon this point can, as far as I can see, never be 

 more than a theory; but it is a matter of course that this theory is greatly streng- 

 thened by the facts that two scientists, in different parts of the globe, have arrived 

 quite independently and simultaneously at quite the same result. 



In accordance with my discoveries and starting from the new facts gathered 

 from Mr. KRYGER'S note-books from his journey in Jutland, I shall now in a 

 somewhat abbreviated form give an account of my investigations, then mention the 

 results of ROUBAUD and finally discuss the relatively slight differences between his 

 and my statements. All in all I suppose it will be understood that the old saying 

 that two eyes see better than one has been corroborated also in this case. 



With regard to the anatomy and general biology of A. maculipennis I refer the 

 reader to the many papers published upon this subject especially: GRASSI 1901 ; 

 IMMS 1907 and 1908; CHRISTOPHERS 1901, NUTALL and SHIPLEY 19001903 a. o. I 

 especially wish to point out the last-named admirable investigation relating to the 

 anatomy of imago and larva ; of particular interest is the study of the digestive organs. 

 (1903 p. 166). 



1. The explorations have been carried on over North, Middle, and South-See- 

 land, over the islands Lolland and Falster, and over a large part of Jutland (see 

 above). From these explorations, carried out in more than a hundred farms, it may 

 be supposed that almost every stable in the country at special times of the year 

 harbours A. maculipennis. In the time from June September A. maculipennis has 

 been found in every stable hitherto explored. From the exploration hitherto carried 

 on it has been quite impossible to point out special areas of distribution where A. 

 maculipennis either preponderates or is rare; I once thought that the mosquito was 

 more common in the southern part of the country, but this is certainly not right. 

 In the woodlands, on the vast meadows on the southern coast of Lolland-Falster, 

 in the marshes at the west coast of Jutland and over the sandy country of Mid- 

 Jutland the mosquito seems everywhere to be common. Most probably the peculiarly 

 regular distribution over the country is in accordance with the fact that breeding 

 places are to be found everywhere and that want of food cannot exist. 



2. The mosquitoes appear in the stables on the first days of May, at that 

 time the number is but small and during the whole of May it is not augmented ; at 

 that time we only find females; in the middle of June the new summer generation 

 appears, making known its existence rather suddenly by means of rather numerous 

 males and an enormous amount of females. Any augmentation of females from the 

 latter part of July I cannot ascertain; the males almost totally disappear, but in the 

 last part of August I have got the impression that the number is again augmented. 

 From the middle of September to November the number of both males and females 



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