THE CONQUEST OF DISEASE 



the heart of this brave and gentle man ! These 

 men gave humanity the knowledge which if 

 applied will make yellow fever an extinct dis- 

 ease. Why did the French fail to dig the canal 

 through the Isthmus of Panama, and why is 

 the canal zone now a veritable sanitorium? 

 The world now knows the answer. And why 

 will it be possible in a few years to make the 

 passage from the Atlantic to the Pacific with- 

 out circumnavigating South America? Be- 

 cause Reed and Lazaer and Carroll made their 

 experiments with mosquitoes and men amid the 

 pestilential swamps of Cuba. 



Malaria. The story of malaria is the same. This dis- 



ease is caused by a protozoan parasite injected 

 into the blood by a particular variety of mos- 

 quito. The parasites enter the red blood cor- 

 puscles, grow to maturity and destroy the blood 

 cells. Each new generation is matured in a 

 certain cycle of time, usually forty-eight hours. 

 There is no uncertainty about these organisms ; 

 they are easily studied by the microscope in all 

 of the stages of their development. Their life 

 history and habits are as well known as those 

 of the elephant. 



For centuries the Pontine marshes near 

 Rome were known to be infected with malaria, 



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