162 PATHOGENIC ORGANISMS 



pasteurisation of the old supply has, in many cases, led to an 

 abatement of infantile diseases and this would indicate that an 

 excessive number of bacteria of all kinds and not any particular 

 group is responsible for the effects observed. (Park and Holt. 21 ) 



Scholberg and Wallis 22 suggest that the prejudicial effect 

 is due to physical and chemical changes produced by bacterial 

 contamination. They found that the products of proteoclastic 

 digestion appear in milk as the atmospheric temperature in- 

 creased and that the albumoses and peptones so produced may 

 be toxic to infants. 



Morgan and Ledingham, 23 in 1909, made an investigation 

 of the bacteriology of summer diarrhsea and concluded that a 

 non-lactose fermenting, non-liquefying organism which they 

 isolated and which is now usually known as Morgan's Number 1 

 Bacillus, bore a close relationship to the disease. 



Lewis, 24 Ross, 25 O'Brien 26 and Orr, 27 made numerous exami- 

 nations of the faeces of infants and, although they found that 

 the non-gelatine liquefying, non-lactose fermenters were ab- 

 normally prevalent in the cases of diarrhea, they could not 

 establish any definite causal relationship. In 1911, Lewis 28 

 and Alexander 29 made further observations on this group and 

 showed that Morgan's No. 1 Bacillus was conspicuously fre- 

 quent in the faeces of infants having epidemic diarrhoea. In 

 the same year Graham Smith 30 found that the non-gelatine 

 liquefying non-lactose fermenters were especially prevalent 

 in flies during the seasonal prevalence of diarrhoea and that 

 Morgan's No. 1 Bacillus, whilst rarely present in flies from 

 houses not containing diarrhoeal cases, was frequently found in 

 houses associated with this disease. 



Lewis 31 pointed out the importance of applying the agglu- 

 tination test to the various organisms which gave the usual 

 fermentation reactions for Morgan's No. 1 Bacillus. 



The etiological relationship of Morgan's No. 1 Bacillus to 

 epidemic summer diarrhoea is not yet fully established, but the 

 evidence in favour of this hypothesis is undoubtedly strong and 

 points to the infection of the milk supply in the home by flies. 



