46 MOSQUITOES 



irritation of the wound is slight in cold weather and only 

 becomes intense during- great summer heat." 



The purpose of the mosquito i)oison has been a sub- 

 ject of some conjecture. The old Reaumur hypothesis, 

 that it causes the blood to become more liquid and more 

 readily sucked ujj by the mosquito, has had its adherents. 



Fig. 3. — Salivaiy glands of Culex at right, Anopheles at left : greatly 

 enlarged. (After Christophers.) 



Osten Sacken and Miall, however, believe that it is prob- 

 able that the piercing mouth-parts of the mosquito were 

 originally acquired for the jDurpose of sucking the juices 

 of plants, and Macloskie advances the idea that the chief 

 food of mosquitoes is not animal blood but the proteids of 

 plants, and that probably the poison ejected may prevent 



