7 8 



Tlic blood of niMii ui)()ii which the mosquito has been feeding can 

 readily be studied in thin sections of the Insect properly stained. In some 

 of the slides which I will pass around, the distended stomach, filled with 

 blood, can be easily distinsnished; under a high magniiication any Plas- 

 modium malariao in the corpuscles can be seen. 



From the preceding remarlvs it will be scon that tlircc chief factors are 

 Involved in this question: 



1. The fever-stricken human being, or. the disease in the body, or, 

 in other words, the reaction brought about by tlie presence of the active 

 cause. 



2. The cause itself, the Plasmodium malariae. 



3. The transmitting agent, carrying the active cause from one in- 

 fected human being to others. This is the Anoplieles mosquito. 



Now what is to be said on the application of all tliese discovered 

 facts? Most of us, unless we see a well detined application for newly 

 discovered facts, are not inclined to attach any great importance to 

 such discoveries, and. on the other hand, the more directly we are con- 

 cerned the greater the value to us. In the field of medicine the value of a 

 discovery is estimated in the light of the relief it gives manliind from 

 disease and atniction. 



How best to apply this new liuowledge in reducing the ravages of 

 malaria and in banishing it from the face of the earth is a question on 

 which opinions differ. By some it is held that the best method of pro- 

 cedure is to destroy all the mosquitoes, and thus prevent the transmission 

 from o]ie individual to others. It is claimed by advocates of this class 

 that the malarial parasite may not live exclusively in man, but might 

 be inoculated from lower animals. On the other extreme are men wlio 

 aim to exterminate malaria by exterminating the malaria germ itself, 

 by properly diagnosing all malaria cases and administering sufficient 

 quinine; by isolating all such patients and protecting them from mosquito 

 bites. They blame the mosquito less than the infected blood upon which 

 the insect feeds. It would be impossible, they argue, to get rid of all 

 the mosquitoes in any community, much less of those in the whole world. 

 Their reliance Is quinine and screens. 



Besides these extreme views there is what may be called a com- 

 promise, that is: To reduce the number of breeding places of the mosqmto 

 to a minimum, by drainage and drying up all wet places and pools of 



