175 APPENDIX A 



danger which exists in flies carrying bacterial organisms to 

 milk as many other investigators have shown, and the 

 danger resulting from the coincident occurrence of uncovered 

 milk and infected flies is too obvious to need emphasis. 



While one regrets that he should feel almost lost, as he 

 states, in the crowd which proclaims far and wide the 

 relation between summer diarrhoea and flies when he had 

 previously felt like one crying in the wilderness (1909, p. 

 154), it must be acknowledged that Nash did great service 

 in making this fact more widely known when there was so 

 little inclination on the part of medical men to believe it. 



The great difficulty with which we are faced in discussing 

 the question of the relation of flies to the prevalence of 

 summer diarrhoea is that it has not been proved to the 

 satisfaction of most investigators what the specific patho- 

 genic organism is, or perhaps there are associated organisms. 

 Morgan (1906-7) isolated a bacillus which he designated 

 " No. 1," and which appears to be an important factor in 

 the causation of the disease. In a further paper Morgan 

 and Ledingham (1909) give a more complete account of 

 their researches on Morgan's bacillus which belongs to the 

 non-lactose fermenting group, to which group all the 

 pathogenic bacteria inducing affections of the intestinal 

 tract belong, namely, the typhoid and paratyphoid bacilli, 

 the dysentery and food-poisoning organisms. In 1905, 58 

 cases of infantile diarrhoea were examined and Morgan's 

 bacillus was found in 48'2 per cent. ; in 1906, in 54 cases it 

 was found in 55'8 per cent.; in 1907, 191 cases were 

 examined and it occurred in 16'2 per cent., and in 1908 it 

 occurred in 53 per cent, of the cases, numbering 166, that 

 were examined. It was found that rats and monkeys were 

 susceptible to infection by feeding and that they succumbed 

 after a period of diarrhoea. One of the most interesting and 

 highly suggestive results of the research was the discovery 

 of Morgan's bacillus in flies. " Batches of flies came for 



