THE MOSQUITO AND MALAKIA 31 



left to Major Ross to demonstrate in a most con\'incing 

 manner that the mosquito was the cause of the spread 

 of malaria. Thus a situation which at one time appeared 

 hopeless is now, on the contrary, full of hope, and the 

 tropics are rapidly becoming possible for Europeans. 



Ross showed, as we shall see presently, that when 

 anopheline mosquitos, not all mosquitos, sucked blood 

 from a person suffering from malaria, that the parasites 

 which they sucked up in their meal of blood developed 

 in their stomach, and, after certain developmental 

 stages, reached the salivary glands, from whence they 

 were transmitted to man again. 



In other words, the anopheline plays the part of 

 intermediate host, just like the dog does in some forms 

 of tapeworm disease, and the cyclops in the case of 

 the guinea- worm disease. It is most important to 

 recollect this, for it proves that the mosquito is 

 necessary to tlie complete life-cycle of the malarial 

 parasite, and that the former does not merely mechani- 

 cally carry the parasite from man to man like the 

 common house-fly does. The latter picks up on its 

 body or mouth parts the infected material, and trans- 

 fers it on to the flrst object it alights upon. We can 

 state the case for the mosquito thus : 



For the complete life-cycle of the malaria parasite, 

 the special mosquito — the anopheline — is as necessary 

 as man. The date when the parasite was discovered 

 in the blood of man, and how Ross proved that it 

 passed part of its life-cycle in the body of the anopheline, 

 will be set forth in a subsequent chapter. 



