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SCIENCE 



[N. S. Vol. XLIV. No. 1128 



ber of careful investigators of malaria and 

 Anopheles than any other region. The fact 

 that certain species of Anopheles occurred only 

 in proximity to man, while others were " wild " 

 was appreciated as early as 1902 and 1903 and 

 it is set forth in the classic " Monograph of 

 the Anopheles mosquitoes of India," by James 

 and Liston (1904). A single brief quotation 

 from Stephens and Christophers will be suffi- 

 cient to demonstrate this. 



Anopheles rossii was found by us always near 

 human dwellings, and often in very foul water. 

 In spite of this commonness of the species, larva? 

 were never found more than a stone 's throw from 

 dwellings. If in any place larvse were discovered 

 at a greater distance, they invariably turned out 

 to be the larvae of other species. A. rossii ap- 

 pears, then, in Bengal to be " f oveal ' ' in its dis- 

 tribution, in contradistinction to other species of 

 Anopheles to be described. 1 



This difference in habits of the different 

 species of Anopheles is generally recognized 

 among workers in India, and one finds fre- 

 quent allusions to it in their writings. 



In Africa, a similar tendency on the part of 

 certain species of Anopheles to associate with 

 man has been noted and a number of authors 

 could be cited in demonstration. 



In America, the interrelation, at least in 

 connection with malaria, seems to have been 

 recognized rather tardily. Knab enunciated 

 and discussed it in a series of papers published 

 during 1912 and 1913 (1, 2, 3, 4, 5). 



His deductions were based, he asserts, upon 

 observations made by the writer in the Panama 

 Canal Zone. The adaptation was indicated 

 very clearly in discussing Anopheles albi- 

 manus, precisely the species, it is interesting to 

 note, which also impressed Major Ashburn. I 

 quote from the original statement. 



While not domestic in the same sense as Stego- 

 myia calopus, Anopheles albimanus is closely as- 

 sociated with man and finds its most congenial 

 surroundings about his habitations and in the con- 

 ditions he creates in the course of agricultural, 

 engineering and other work. This fact is corre- 

 lated with the highly developed blood-sucking 

 habit and has been an active factor in its develop- 



i Eeports to the Malaria Committee of the 

 Boyal Society, London, 6th Series, p. 15, 1902. 



ment and in establishing the economic importance 

 of the species (6). 



The same relation of Anopheles albimanus 

 toward man was observed by another worker 

 in the Panama Canal Zone, James Zetek, and 

 discussed in a paper published in 1915. 



Quoting briefly : 



The writer in his inspection of the Canal Zone, 

 found A. albimanus to breed only near settle- 

 ments. It therefore seems quite plausible to be- 

 lieve that the pathogenic species of Anopheles be- 

 come more and more restricted to human settle- 

 ments, an adaptation which no doubt will hold for 

 all animals which play a role similar to that of 

 albimanus in the transmission of disease (10). 



But too sweeping claims regarding the adap- 

 tation of the malaria-transmitting Anopheles 

 should not be made. The writer, as quoted 

 above, has already indicated that the associa- 

 tion with man is a much looser one than in 

 the case of Mdes calopus, and, it should be 

 added, Culex quinquefasciatus (fatigans). 

 Knab points out that the long period during 

 which the malarial gametes are present in the 

 human circulation effectively compensates for 

 less frequent opportunity for infection of the 

 mosquito. Dr. Adolph Lutz of Brazil even 

 goes so far as to condemn altogether the idea 

 of adaptation in the case of Anopheles (7, 8). 



He asserts that in Brazil, Anopheles albi- 

 manus occurs in uninhabited localities. !Nor 

 will he admit any predilection for man on the 

 part of this mosquito, since he has observed 

 that it prefers the horse to the rider (1. c). 

 In fact, no such predilection has been demon- 

 strated for any Anopheles, except, perhaps, it 

 can be inferred in the case of the Indian 

 Anopheles rossii. That it does not exist in the 

 European Anopheles maculipennis, which un- 

 questionably has had all possible opportunity 

 to develop such a taste, has been very clearly 

 shown by Miihlens (9). Grassi and others have 

 gone on record that the degree of attraction 

 depends upon the size of the animal, a man 

 being preferred to a dog, a horse or cow to a 

 man. 



This much must be admitted in any case; 

 that the highly developed appetite for blood of 

 certain species of Anopheles and frequent op- 



