78 HOUSEHOLD INSECTS 



The parasites set free in the blood may enter other red 

 blood cells, grow, reach maturity, and burst forth again. 

 These, in turn, may go through the same course again 

 and again, producing chills and fevers incessantly unless 

 destroyed by some agency. Finally, there appears in the 

 serum of the blood the male and female individuals of 

 the parasite, but these cannot develop farther until taken 

 into the body of a mosquito. 



History of the parasite in the body of a mosquito. — 

 Suppose while the blood of a malarious person is full of the 

 minute parasites he should be bitten by a mosquito. As 

 the mosquito sucks up the blood some of the parasites 

 would be sure to be taken up with it. After being sucked 

 up into the beak of the mosquito they are carried to the 

 stomach of the insect and there pass through a sexual 

 process. They then enter into the cells of the stomach 

 walls, undergo certain changes, and finally pass through 

 the stomach walls of the mosquito, undergo complicated 

 changes in the body cavity of the insect, and eventually 

 find their way to the salivary glands, from which they 

 are injected through the beak into the blood of the person 

 who is being bitten by the mosquito. There they again 

 enter the red blood cells, pursuing the course already 

 described and causing chills and fevers. 



Summary. — To sum up, then, malaria is caused by a 

 minute animal parasite that lives within the red blood 

 corpuscles of human beings. This parasite destroys 

 millions of the red blood cells that are so necessary to 

 life and, in addition, secretes certain poisonous substances 

 known as toxins, which lodge in various parts of the body. 



Its life history has been traced step by step by many 

 careful observers. 



