108 ELEMENTS OF GENERAL SCIENCE 



vanquished the Spanish, but a far more difficult conquest 

 remained. It is easy to locate and fight a political enemy, 

 but it is very hard to fight ignorance, especially when it is 

 backed by unfounded prejudice. Consequently the Cuban 

 of Havana, who had been set free from Spain, had to be set 

 free from himself. Martial law prevailed until the harbor was 

 cleaned, a new and pure water supply was found, a more 

 sanitary system of sewage disposal was installed, and last, 

 but greatest, those who were in charge of sick people were 

 compelled to sterilize all material containing disease bacteria, 

 so that the agents of transmission did not carry disease germs. 

 Soon average health returned to Havana a conquest of 

 more import than her release from Spain. 



124. Malaria caused by an animal organism. The mos- 

 quito, like the fly, is a carrier of disease germs, but in this 

 case only certain kinds of germs are transmitted, while almost 

 any kind may be carried by the fly. Malaria is the most 

 common disease the germ of which is carried by mosquitoes. 

 In order that we may understand the relation between mos- 

 quitoes and malaria and know how to prevent the latter, 

 we must discuss both the disease and the mosquito. When a 

 person has malaria, his red blood corpuscles are more or less 

 infected with an extremely small one-celled animal. One of 

 these malarial organisms lives within a red corpuscle for a 

 brief period (three days in the case of one kind of malaria), 

 and by the end of that time has undergone repeated divi- 

 sions, resulting in the formation of several of the one-celled 

 animals. The wall of the corpuscle breaks, and all the newly 

 formed malarial parasites are set free in the liquid of the 

 blood. It is usually just after many such parasites are set 

 free in the blood that the paroxysm known as malarial chill 

 ensues. The germs may enter other red corpuscles, and in 

 due time another crop of their kind will have been produced 

 and another chill ensue. We must discuss the life history of 

 the mosquito before continuing the discussion of malaria. 



