272 OUR INSECT FRIENDS AND FOES 



the disease is transmitted from man to man. It 

 is now some twenty years since Laveran, a dis- 

 tinguished French medical man, made his great 

 discovery of the minute animal parasite in the 

 red blood corpuscles of man, which causes 

 malaria; while it was due to the investigations 

 of Golgi that what is termed the developmental 

 cycle of the malarial parasite in the blood was 

 successfully demonstrated. It is this asexual 

 cycle, the febrile cycle, which produces auto- 

 infection of the patient. To Major Ronald Ross 

 belongs the honour and credit of discovering 

 and demonstrating the fact that a further sexual 

 cycle of the parasite is carried out in the 

 stomach of the mosquito, from which new in- 

 fection in a healthy subject is produced. From 

 the joint investigations of these three dis- 

 tinguished men of science we learn that malaria, 

 that terrible disease of the tropics, is due to the 

 presence in the blood of innumerable minute 

 animal parasites, which produce fever, recurring 

 every one, two, or three days, and termed, 

 according to their period, quotidian, tertian, or 

 quartan fever ; and unless the sufferer be 

 treated with cinchona bark quinine the para- 

 sites remain in the body for some years, and, by 

 auto-infection, cause constant relapses of fever, 

 anaemia, and enlargement of the spleen. Exactly 

 how the disease was transmitted was unknown 

 until Major Ross discovered the sexual cycle in 

 the mosquito. 



The mosquitos, or gnats, which transmit the 

 malaria parasite to man, belong to a class called 

 Anophelines, or spot-winged gnats, abounding in 



