Mosquitoes and Malaria 117 



bone marrow for a long time. Under favorable 

 conditions it may again begin the process of mul- 

 tiplication and the patient will suffer a relapse. 



SUMMARY 



Now let us sum up some of the reasons why we 

 believe that the malaria fever can be transmitted 

 only through the agency of mosquitoes. First, 

 we know the life-history of the parasite, it has 

 been studied in both of its hosts. Attempts have 

 been made to rear it in other hosts but without 

 avail, and we know from the general relations of 

 the parasite that it must have this sexual as well 

 as the asexual generations. Second, in some re- 

 gions which would seem to be malarial, that is, 

 where the miasmatic mists arise, no malaria occurs. 

 Why ? Usually it can be definitely shown that no 

 Anopheles occur there. Other mosquitoes may be 

 there in abundance, but if no Anopheles, there is 

 no malaria. In certain regions this is well demon- 

 strated. The west coast of Africa is one of the 

 worst pest-holes of malaria and Anopheles. The 

 east coast has no malaria and no Anopheles. In 

 many islands the same condition exists. On the 

 other hand, the Fiji Islands have Anopheles but 

 no malaria. No malaria has ever been introduced 

 there to infect the mosquitoes. In the same way 



