DIPTERA OF MINNESOTA. 51 



this or by some other means, the spores in the corpuscles break out into 

 the serum, and other corpuscles are attacked. The development to 

 this point will take place, according- to authors, anywhere, even on 

 a glass slip under the microscope, in the stomach of the genus of 

 mosquito known as Culcx, and it is quite likely in the stomachs of 

 various other biting insects. - But as far as wc know it is only in 

 the stomach of Anopheles that the manner of development changes 

 to a different form and finally penetrates to the duct of the salivary 

 glands of the above mosquito ; thence, when the insect is biting, 

 through the proboscis these enter the blood of the victim, who is 

 thus inoculated with the malarial germ, and shortly after shows the 

 well known symptoms of the disease. It is now known that malaria 

 is not caused by the air of swampy districts ; that the swampy areas 

 are only secondary in affording breeding grounds for mosquitoes ; 

 and that, as far as our knowledge goes at present, the only natural 

 way by which the disease can be transmitted is through the bite of 

 one, and only one insect, the mosquito we know as Anopheles. 



In Italy, on the Campagna and elsewhere, a series of careful 

 experiments were made to demonstrate that individuals had to be 

 bitten by malaria-bearing mosquitoes in order to become infected. 

 In 1900 certain experimenters lived in the most malarial infested 

 region of the Campagna during the malarial period. They entered 

 screened houses at sundown, and remained there until daylight, thus 

 avoiding being bitten, while people all about them, not protected as they 

 were, became affected with the disease, particularly at the advent of the 

 rainy season. The doctors referred to, although they- were frequently 

 wet through by being exposed to the rain, showed not the slightest 

 symptoms. Check experiments have been made b}' allowing speci- 

 mens of Anopheles which had fed upon the blood of malarial patients 

 at Rome to bite an individual not aft'ected, and who had not since a 

 boy, and was not at the time, living in a malarial district. In other 

 words, the mosquitoes after biting the patient in Rome were sent to 

 London. At the proper time malarial symptoms appeared in the in- 

 dividual, and the parasites Avere found in his blood. 



Just as malaria is transmitted by the bite of a mosquito, so it 

 is with the yellow fever. Most conclusive proofs are present to es- 

 tablish this fact. That the disease is not spread by contact was 

 demonstrated to the whole scientific world bv volunteer observers 



