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THE ETIOLOGY OF TROPICAL DISEASES 



indeed, anything in which a little water can lodge. They are 

 almost domestic animals. The palpi are short, the wings unspotted, 

 the proboscis thin, the thorax large, and the larvae have breathing 

 tubes. They prefer to lie in artificial collections of water. When at 

 rest, for example on a wall, the body of Culex is found parallel to the 

 wall (see fig. 33). The rarer species, and that which has been proved 

 to be the host of the malaria parasite, is the Anopheles. This differs in 

 various essential particulars from the Culex. In Anopheles the body 

 is slim, but the proboscis long and thick, the palpi are long, and the 



FIG. 33. Diagram of Culex and Anopheles on Wall (Ross). 



wing is "dappled" with dark spots on its anterior margin. The 

 larvae have no breathing tubes, and lie horizontally (not vertically 

 as in Culex) in the water of puddles, looking like bits of brown 

 stick or thorns floating on the surface. When at rest on a wall, the 

 axis of its body is almost at right angles to the wall, so that the 

 head of the Anopheles is directed towards the wall, whilst the body 

 projects out into the room. Culex has been briefly designated a 

 " pot-breeding " mosquito, whilst one of the features of Anopheles is 

 that it is " puddle-breeding." Its favourite haunts are slow, small 

 streamlets containing algae ; small, shallow, natural puddles with 

 confervoid growths in the water ; or stagnant and fairly permanent 



