156 MALCOLM EVAN MACGREGOR. 



The connection between malaria and the mosquito had long been held, it is said, 

 by the Italian and Tyrolese peasants, and even by the natives of East Africa, but the 

 first charge brought against the mosquito in the spread of disease, by scientific 

 authority, was in connection with yellow fever. In 1853, Dr. Daniel Beauperthuy, 

 a French physician, wrote ably arguing that yellow fever and other fevers were trans- 

 mitted by mosquitoes, but in those days there being no accepted belief in a contagimii 

 vivum, he concluded that the virus was obtained from decomposing material that the 

 mosquito had consumed and that was later accidentally inoculated into man. 

 Raimbert, in 1869, showed by experiment that anthrax could be disseminated by 

 flies. 



Epoch-making in the history of our knowledge of insect vectors was Manson's 

 discovery, in 1878, that Filaria bancrofti was spread by mosquitoes ; but at first he 

 thought the Filaria escaped from the insect into water and reached man in this 

 manner. Later work by Manson and his colleagues determined the exact means of 

 transmission. 



It was not until 28 years after Beauperthuy's theory that Charles Finlay, an 

 American of Havana, definitely attributed, in 1881, the transmission of yellow fever 

 to a mosquito of a definite species. He had noticed the connection that seemed to 

 exist between the presence of large numbers of Stegomyia fasciata and the prevalence 

 of yellow fever. He then attempted to transmit the disease experimentally by the 

 bites of this mosquito, and whilst his experiments are open to criticism, there is no 

 doubt that he did succeed in doing so. 



Three years later, in 1883, another American, A. F. A. King, advanced the first 

 well-formulated mosquito- malaria theory, and in 1898 Ross, in India, demonstrated 

 beyond doubt the important role played by mosquitoes in the transmission of malaria. 



In 1899 the American Yellow Fever Commission (Reed, Carroll, Lezear and Agra- 

 monte) was sent to Cuba and was there able to demonstrate with certainty that yellow 

 fever is transmitted by S. fasciata. 



It is interesting thus to note the almost parallel development in time of our know- 

 ledge of two of the most important insect-borne diseases. To deal even briefly with 

 the historical aspects of our knowledge of other diseases tabulated below would be to 

 consume a large amount of space, and the foregoing account will have indicated the 

 path that has led to subsequent discoveries whose histories are readily available. 



I will pass therefore to a few notes on each of the Tables. 



Notes to Table I. — Diseases of Unknown Origin. 



The majority of these diseases are doubtless caused by living viruses, often 

 organisms of ultra-microscopic size, and commonly referred to as " filterable viruses/' 



In the case of pellagra it would appear, however, from the most recent work that 

 although it is still considered by many persons to be possibly an insect-borne disease 

 (and according to Sambon having a likely vector in either the Ceratopogoninae or 

 Simuliidae) Goldberger in America considers it a disease now certainly attributable 

 to vitamine-starvation through an unbalanced diet. If this is the case, there is no 

 causative organism and no vector, and pellagra should be ruled out of present con- 

 sideration. The question nevertheless is by no means settled. 



