32 The Ottawa Naturalist. [May 



From the first of these he obtained 30 colonies comprising six 

 kinds of bacteria and six colonies of four species of fungi. From 

 the second he obtained 46 colonies comprising 8 kinds of bacteria, 

 and 7 colonies of four species of fungi, and from the fly caught 

 on the dust bin he obtained 116 colonies comprising 11 kinds of 

 bacteria, one of which is only found in the intestinal tract, and 

 10 colonies of six species of fungi. 



It does not require any play of the imagination therefore, to 

 appreciate the ability of house-flies, if they normally infect 

 them.selves in this manner and carry about such germs, to infect 

 themselves with the bacilli of typhoid fever, tuberculosis, 

 infantile diarrhoea, and other similarly infectious diseases. 

 Typhoid bacilli have been obtained from flies frequenting places 

 where the disease existed. It has been found that such flies will 

 remain infected for some time, and also that typhoid and 

 tubercular bacilli can pass through the digestive tract of the 

 fly in a virulent condition and that their dejecta are infective. 

 It has further been demonstrated that flies reared from maggots 

 which have been bred in matter infected with tvphoid bacilli 

 are infected with the bacillus. In the South African and 

 Spanish-American wars flies were responsible for more deaths 

 than bullets. Enteric fever in those wars carried off its thousands, 

 which was not to be wondered at, in view of the prevailing 

 sanitary conditions with open latrines frequented by incipient 

 cases of enteric and invriads of flies swarming indiscriminatelv 

 about the latrines and the mess tents. On a smaller scale 

 similar conditions occur in the unsanitary districts of our tovv^ns 

 and cities where the house-flies frequent indiscriminatelv and 

 in turn the privies and kitchen tables Once typhoid establishes 

 itself in such places the house-flies will account for the subsequent 

 spread of the infection. The warmer the weather the more 

 active will the flies be, and with greater ease and rapidity will 

 the disease be spread. 



An allied disease, infantile or summer diarrhoea, is responsible 

 for the greatest mortality among young children during the 

 summer months or third quarter of the vear. The specific 

 cause of this disease has not been satisfactorily determined as 

 yet, but it is probably a germ allied to the typhoid bacilli, and, 

 in the same way that we know that the mosquito carries the 

 germ of yellow fever, although it has not as vet been discovered, 

 it is fairly certain from statistical and circumstantial or epi- 

 demiological evidence that house-flies are the chief agents in 

 the dissemination of this disease. I have prepared a chart extend- 

 ing over a period of twentv vears and giving the number of deaths 

 per thousand living due to this disease, and the mean temperature 

 during the third quarter of the vear in a large English citv, and 



