666 INFECTION AND IMMUNITY. 



Migration of The anopheles leads an adult life for many 

 months and may even hibernate under suitable 

 conditions either in the adult or larval form. It 

 is generally stated that the insects do not fly more 

 than half a mile from their breeding and feeding 

 grounds. Their dispersal certainly extends beyond 

 these limits, however. James and Listen enumer- 

 ate the following methods of dispersal: (1) by 

 direct flight over considerable distances; (2) by 

 the eggs and larvae being carried in streams and 

 canals; (3) by a multiplication of successive short 

 flights by adults; (4) in conveyances. 



Anopheles avoids high winds and rains, seeks 

 shelter on excessively hot days and feeds and bites 

 chiefly or only after sunset and before sunrise. 

 The latter habit confirms the old belief that ma- 

 larial infection occurs chiefly at night. 



For further details as to the morphology and 

 habits of the insect in its different stages, and for 

 differentiation of the different genera and spe- 

 cies, one should consult a textbook of entomology, 

 or, for example, the book on "Mosquitos," by How- 

 ard (McClure, Phillips & Co., New York). 



prophylaxis. Individual prophylaxis may be accomplished and 

 maintained by taking small daily doses of quinin, 

 or larger doses (1 gram) every few days. One who 

 has had malaria may likewise prevent recurrence 

 by suitable quinin treatment. Quinin has the 

 power of preventing division of the parasites, and 

 therefore, the power of preventing the paroxysms. 

 "K. Koch's procedure consists in this, that one 

 takes a gram of quinin every tenth and eleventh 

 day, and if fever still develops, every ninth and 

 tenth day." (Ruge.) 



