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Science, pi'ovfd that flies were the infection-carriers of 

 tuberculosis. Experiments have shown that flies absorbed tuber- 

 culosis bacilli from the expectorations of consumptive patients. 

 These bacilli were distributed partly by means of the insects' excre- 

 ment and partly, as the Hies soon afterwards died, by their decaying 

 bodies. The expectoration of consumptives should therefoie 

 be deposited in covered vessels and destroyed, The part which 

 the Mosquito plaj'S in the history of Filaria sanguinis hominis, 

 Lewis has been proved. This worm which is several inches 

 long, lives in the tropical zones — India, China and l"?razil. It 

 is found in the human blood and in the lymphatic glands. 

 It is the cause of many painful diseases— tumours, elephantiasis, 

 bloody urine. &c. According to one authority, Patrick Manson, 

 the history of the worm is as ibilows : Its small eggs are depos- 

 ited in the blood where they develop into embryos. Strange to 

 say they live during the day in the heart and great arteries. It 

 is only during sleep they invade the small veins of the extrem- 

 ities. Every drop of blood taken from the finger or the ear 

 during sleep Avill then contain a number of embryos. They are 

 also found in the urine and the tears or secretions of the 

 lachrymal glands, and, consequently, it can be easily understood 

 how they reach water. Mosquitoes also carry them to water. 

 The female Mosquito when filling itself with blood from its 

 sleeping human victim also absorbs Avith the blood a number of 

 these embryos. Having filled herself with blood she flies to 

 to her home, the water, in the vicinity of Avhich she spends her 

 time slowly digesting her meal and in maturing her eggs of 

 which she ultimately lays about iiOO. The embryos while in 

 the Mosquito undergo a change and in a period of from six to 

 seven days attain a length of J^ m.m. As soon as the Mosquito 

 thus infected has deposited her egg's she dies, and her body 

 falling into the water the worm embryos are set at liberty. 

 They remain in the water awaiting their arrival at their perfect 

 state which is only attained when they have been introduced 

 into the human body. This shows how necessary it is in the 

 tropics, never to drink water vinless it has been first filtered or 

 boiled. It is noAV generally understood that our studies in 

 disease germs are as yet only in their primary stage, but un- 

 doubtedly the germs of many diseases depend largely for their 

 propagation and distribution upon the medium of blood-sucking 

 insects. Facts such as these have brought many different Flies and 

 Mosquitoes under the notice of medical men and students of 

 hygiene in a light which the Zoologists who have studied thtse 

 insects have never viewed them. 



2nd December. 1892. 



