270 



MALARIA 



native town and European quarters are built. 

 This creek is at a distance of about half a mile 

 from the houses mentioned." 



It fs plain, from these and other instances given 

 by the members of the Nigeria Expedition, that a 

 modified sort of "segregation" can be effected in 

 many places, without any injury either to native 

 feelings, or to politics, or to commerce ; and that by 

 such segregation the risk of malaria among 

 Europeans in Africa would be diminished. 



3. Protection against Anopheles. " Grassi is of 

 opinion," says Dr Manson, " that the malaria 

 parasite, under natural conditions, can be acquired 

 by man only through the bite of the mosquito, and 

 that the mosquito can acquire the parasite only by 

 ingesting the blood of a malaria-infected man. He 

 holds that there is no other extracorporeal life than 

 that described ; that there is no authentic instance 

 of malaria being acquired in uninhabited places ; 

 and that in the case of malaria in connection with 

 soil disturbances, it depends on the creation, during 

 digging operations, of puddles of water in which 

 Anopheles breed." Manson, every page of whose 

 book {Tropical Diseases, second edition, 1900) must 

 be carefully studied on this subject, is inclined to 

 believe that the parasite may perhaps be capable of 

 living in the blood of other vertebrate hosts, or of 

 passing from mosquito to mosquito ; and that it 

 may, under certain conditions, lie dormant in soil, 

 and thus be transmitted in air, or water, or food, to 

 workmen turning the soil. But all authorities are 

 agreed that, practically, the fight against malaria 



