INSECTS 49 



only during night time, " loving darkness, rather than light, 

 because her deeds are evil." 



In the year 1890 Dr. Manson and Dr. Warren, two physi- 

 cians in London, allowed themselves to be bitten by Ano- 

 pheles mosquitoes that had previously bitten malaria pa- 

 tients in Italy. In eighteen days both developed malarial 

 fever and in the blood of both, malaria organisms were found, 

 although previous to this infection from the mosquito 

 neither had suffered in any way from the disease. 



40. Life history of the malaria parasite. But yet more wonder- 

 ful proof that the mosquito transmits malaria has been furnished 

 by the microscopes of biologists. The discovery of the malarial 

 parasite by Laveran in 1880 has already been referred to. This 

 resembles in its form and activities a single-celled animal known as 

 the Amoeba (124). When this organism of malaria is present in 

 human blood, it bores its way into a red corpuscle (H. B., 6), feeds 

 upon the contents of this blood cell, and grows at the expense of the 

 corpuscle until the parasite occupies nearly all the space inside it 

 (Fig. 33). The malaria parasite then divides into a number (6-16) 

 of daughter parasites, which rupture the red corpuscle in which they 

 have been developing, and escape into the liquid part of the blood, 

 thus causing the chills so characteristic of malaria. Each new para- 

 site then attacks a new corpuscle and at the end of two or three days 

 produces six to sixteen new spores, and so the organisms multiply. 



Now here comes the relation of the mosquito to malaria. For 

 when the female Anopheles bites a person having malaria, she is 

 likely to suck up blood that contains malaria organisms in a cer- 

 tain stage of development. These reach the insect's stomach, where 

 they pass through a stage known as fertilization. In the stomach of 

 a single mosquito as many as five hundred of these fertilized cells 

 have been counted. Each cell then becomes pointed at one end, 

 bores its way through the wall of the mosquito's stomach, and in 

 fifteen to twenty days produces relatively large swellings on the 

 outer surface, in which are thousands of needle-shaped malaria 

 spores (Fig. 33). 

 E 



