SUMMER DIARRHCEA 169 



in flies Table 23 has been constructed. As far as possible from the data given the 

 bacilli described by Lewis (1911 and 1912), O'Brien (1911), Orr (1911), Ross (191 1) 

 and Alexander (191 2) in fsces have been tabulated according to the scheme which has 

 been explained. The results of the examinations of flies have also been recorded. 



It will be seen that bacilli belonging to group A are occasionally found in the 

 faeces of healthy children, and of those suffering from diarrhoea. They occur in about 

 2 % of flies from all sources. Bacilli belonging to group B, sub-group a, seem to 

 occur more commonly in the fa?ces of children suffering from epidemic diarrhoea than 

 in the fseces of healthy children, and they are twice as often found in flies from 

 infected houses as in flies from non-infected houses. Bacilli belonging to sub-group m 

 have seldom been found in faecal material, but occur in about i'S^/q of flies from all 

 sources. Bacilli belonging to sub-groups j, k, 1, n, o, and p are very rare. 



Bacilli belonging to group C, sub-group a, occur moderately frequently in the 

 faeces of children suffering from epidemic diarrhoea, but are very frequently found in 

 flies (11%; from infected houses 14 %, from non-infected S^/o)- Bacilli belonging 

 to sub-groups b, c, d, e, f, and h are seldom met with. Bacilli belonging to sub-group 

 g have rarely been isolated from faeces, but are very common inhabitants of the fly's 

 intestine (12 "/o)- (See p. 117.) Bacilli belonging to groups D, E and F are very 

 rarely encountered. 



As already seen bacilli belonging to group G, sub-group a, are of special interest, 

 and will be discussed later. Those belonging to sub-groups b, e {a), f, i(a), i (a), j (a), 

 k, k {a), m, m (a), o {a), p, and p {a) are seldom met with. Bacilli belonging to group H, 

 sub-group a, are occasionally found in the fceces of children, and occur in about 2 "/o 

 of flies from all sources. Those belonging to sub-groups b, c, c (a), c {d), d, e, e {a), 

 f, g, and h are uncommon. 



Bacilli belonging to groups I, J and K are sometimes found in fjeces, but have 

 never been isolated from flies. 



It will be seen from the foregoing account that flies often harbour bacilli which are 

 found in the excreta of children, and it is probable that they often infect food materials 

 with bacilli belonging to groups A, B (sub-groups a and m), C (sub-groups a and g) 

 and H (sub-group a). There is at present, however, little evidence that any of these 

 varieties produce pathogenic effects in children, though Lewis (191 1, 1912) and 

 Morgan and Ledingham (1909) have shown by feeding experiments that some 

 members of all these groups are pathogenic for rats and mice. 



In regard, however, to the varieties of bacilli composing the sub-group a of 

 group G, evidence to show that they are very frequently present in the faces of 

 children suffering from epidemic diarrhcea, in some outbreaks, has already been 

 quoted. 



Through the kindness of Dr Robertson I was enabled to examine flies caught in 

 53 houses in Birmingham in which cases of epidemic diarrhcea had occurred. 

 Dr Lewis examined the fasces of the patients living in 49 of these houses. I am, 

 therefore, fortunate in being able to compare, through the courtesy of Dr Lewis, the 

 varieties of bacilli in the faeces of the patients with those isolated from flies caught in 

 the houses in which they lived. Dr Lewis obtained bacilH of the Ga type (Ga 8 = 34, 

 Ga4=i, Ga7=i) from the faeces of patients living in 36 {7470) of these houses. The 

 present writer found bacilli of this group in flies from 10 of these houses. In the 

 faeces of patients living in the other 1 3 houses Dr Lewis did not find bacilli of this 

 type. 



If the data are further analysed the results are found to be stdl more remarkable. 

 No satisfactory examinations could be made of the flies from 10 of the 36 houses in 



