MEDICAL ENTOMOLOGY 



It will be remembered that, in our consideration of economic ento- 

 mology in North America, in Part I, we devoted some time to the 

 consideration of the extraordinary events of the last decade of the 

 nineteenth century which served to focus universal attention on ap- 

 plied entomology. One of those events was the proof of the carriage 

 of disease to human beings by insects. That, however, was a dis- 

 covery by no means confined to America, and was not only of world- 

 wide importance, but investigations in that direction were begun im- 

 mediately by men in all parts of the world. It therefore deserves 

 consideration in a section that will not be limited geographically. 



Medical entomology, although so important today, extending as it 

 does in numerous directions, is of very recent development. The 

 first exact proofs of the carriage by insects of disease organisms was 

 gained less than 50 years ago. It is true that here and there sugges- 

 tions had been made as to the role of insects in the carriage of dis- 

 ease for many years previously. The idea seems to have sprung up 

 and gained ground among the aboriginal peoples of India, Africa, and 

 South America ; and even on the Roman campagna, a home of 

 malaria, the poor peasants long ago connected the idea of mosquitoes 

 with the idea of fevers. And nearly a hundred years ago two medical 

 men, Dr. Josiah Nott, of Mobile, and Dr. Louis D. Beauperthuy, of 

 the West Indies, argued that mosquitoes were instrumental in the 

 carriage of yellow fever. 



But all this was before the era when the medical world learned, 

 through Pasteur and his school, that the old humoral and vitalistic 

 doctrines concerning disease were wrong, and that a great number of 

 diseases have as their only causes infinitely minute beings of both 

 animal and vegetable nature which penetrate the bodies of warm- 

 blooded animals and produce not only specific lesions but general 

 disease. The Pasteur discoveries related only to bacteria. He was 

 followed by hundreds of workers who showed that other parasitic 

 organisms exist and that these organisms are excessively variable in 

 type, in biology, and in resulting diseases. Some of the higher of 

 these forms — the parasitic worms — were discovered before Pasteur ; 

 and the first parasitic Protozoan, causing dysentery, was found a few 

 years before Pasteur's bacterial discoveries were announced. And 

 then followed the discovery of the Spirochaete of relapsing fever, 

 the Ameba of tropical dysentery, the Protozoan cause of malaria, the 



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