44 31 OS QUI TOES 



to count the larvio in .an ordinary rain-water barrel. On 

 July 6th, the water in one barrel was filtered and was 

 found to contain 17,259 e<^gs, larva? and pupje. On July 

 22d, 10,110 additional ones were counted. If anyone is 

 mathematically inclined, let him assume that half of these 

 developed into female mosquitoes, each one of which laid 

 400 egg's, and that twelve generations l)reed in a summer 

 in the northern United States. It will then be perfectly 

 obvious that a large neighborhood may be well supplied 

 with mosquitoes from a single neglected rain-water barrel. 



The Poison of Mosquito Bites. 



That fine old observer, Reaumur, rather thought that a 

 poisonous fiuid was secreted by the mosfpiito and that 

 its purpose was to cause the blood to fiow more readily 

 when it bites. Later observers have acceptcnl this state- 

 ment, or have denied the existence of such fiuid, stating 

 that the swelling following the ])ite Avas caused by the 

 irritation of the i)uncture, without the aid of poison. 

 Dimmock (1881) convinced himself that a poisonous saliva 

 was introduced. He noticed that if tli(^ mosquito ])unc- 

 tures the skin without entering a ])]()od-vessel, although 

 it may insert its proboscis for nearly its full h^ngth, nt) 

 poisonous eft'ect is produced upon the skin ; but when the 

 proboscis strikes blood and the insect draws its fill, the 

 subsequent swelling and ])()isonous efiect are obvious. 

 He argued that these efircts indicate a cmistant outpour- 

 ing of some sort of poisonous fiuid during the blood- 

 sucking process. 



