362 PATHOGENIC BACTERIA IN MILK 



nidus and as pabulum in undergoing various phases of its life 

 history. 



" That in food, inside as well as outside the human body, such 

 micro-organism finds, especially at certain seasons, nidus and pabu- 

 lum convenient for its development, multiplication, or evolution. 



" That from food, as also from the contained organic matter of 

 particular soils, such micro-organism can manufacture by the 

 chemical changes wrought therein through certain of its life 

 processes a substance which is a virulent chemical poison ; and that 

 this chemical poison is, in the human body, the material cause 

 of epidemic diarrhoea."^ 



It will be observed that the three causal agents which Dr 

 Ballard mentions as playing a large part in the production of this 

 disease are the soil, season, and food — and the causa causans is 

 " some micro-organism not yet detected or isolated." It must be 

 said that we have not got much further than this during the last 

 fifteen years. We do not yet know what is the " virulent chemical 

 poison " which produces the chemical and morbid conditions of 

 the disease. If anything, however, additional knowledge lays added 

 emphasis upon the relationship of food, and more particularly milk, 

 as the main channels of infection. To this matter reference will 

 subsequently be made. 



Bacteriology of diapphoea. — In 1885, Escherich published his 

 classical researches on B. colt cotmnunis. He pointed out that the 

 meconium of the newly-born infant is free from bacteria, but by the 

 second day they are present in large numbers, and in the ordinary 

 excreta of healthy infants he found chiefly two organisms, B. lactis 

 (zrogenes and B. coli communis. Of these the former was the more 

 abundant in the upper part of the small intestine, and the latter in 

 the lower part and in the colon, so that in the excreta B. coli was 

 abundant, and B. lactis comparatively scarce. Booker, working in 

 1886 and onwards, found that the constant bacteria of the healthy 

 excreta of the infant {B. coli and B. lactis cBrogenes) do not disappear 

 in the excreta of diarrhoea. B. coli, however, does not predominate 

 in the same degree, and B. lactis is present generally in greater 

 numbers than in the healthy excreta. Booker examined the 

 excreta of 31 children, and isolated 33 different species of bacteria. 

 Many varieties of bacteria are sometimes found in individual cases 

 of diarrhcea. The greatest number were found in cases of cholera 

 infantum, and a larger number in catarrhal enteritis than in 



^ Supplement to the Report of the Medical Officer of the Local Governtnent 

 Board, 1887. 



