15 



short by the fall in temperature usually occurring in 

 September, but reaches a maximum in October and 

 November that is, at a time when there are hardly any 

 flies about. Whether, as Dr. Niven believes, increased fly 

 prevalence is a factor in determining the increasing incidence 

 in Manchester and London at the end of the summer, it 

 seems to me impossible to say ; but, taking into account the 

 circumstantial evidence against the fly, this may not unlikely 

 be the case, but it is clear that other causes are operative and 

 that epidemics of typhoid fever occur in these cities in the 

 absence of flies. 



This is in striking contrast to the observations in military 

 camps both during the Spanish- American War and the Boer 

 War. In both these instances, with the onset of cooler 

 weather and the first frosty nights, the nuisance from flies 

 was as once relieved and the cases of enteric fever diminished 

 shortly afterwards. 



Flies in Relation to Infantile Diarrhoea. 



As the infective agent of infantile diarrhoea has not been 

 identified, no direct evidence that flies do on occasion 

 convey the germs of this disease is available. It is probable 

 that more than one etiological factor for infantile diarrhoea 

 exists. Different organisms have been found to be par- 

 ticularly prevalent in the stools in different epidemics in 

 various localities. In America some of the epidemics have 

 been associated with the presence of a dysentery bacillus 

 (. Flexner) in the stools Wollstein (1903), Park (1903), 

 Duval and Schorer (1903), Cordes (1903), Weaver and 

 Tunnicliffe (1905). In other epidemics in Arrferica no 

 dysentery bacilli were found, and an epidemic in Vienna 

 investigated by Jehle and Charleton (1905) was not found 

 to be associated with dysentery bacilli. Metchnikoff (1909) 

 is of opinion that B. vulgare is the causal organism. 



A search for evidence of a causal agent was conducted 

 on a large scale by Morgan (1906, 1907, 1909) and 

 his colleagues of the Lister Institute during the epi- 

 demic in London in the years 1905, 1906, 1907, 

 and 1908. The search was restricted to aerobic bacilli 

 which neither fermented lactose nor liquefied gelatin i.e., 

 to a group which includes the dysentery, typhoid and para- 

 typhoid, and Gaertner bacilli. Stools and necropsy material 

 were examined from several hundred cases of the disease, 

 and from other children. A very large number of organisms 

 were isolated and examined, but the only one whose pre- 

 valence was found to be related to infantile diarrhoea 

 was a non-motile bacillus of the above group, which was 

 peculiar in that it failed to ferment mannite. It is now 

 generally known as Morgan's bacillus No. 1. This organism 

 was not infrequently recovered from the organs in fatal 



