150 THOMPSON YATES LABORATORIES REPORT 
To sum up, the bacillus enteritidis was first discovered in connection with a 
specific epidemic of diarrhoea. It was thought that this bacillus probably caused the 
outbreak, because it was assumed to be an uncommon organism, and was present in 
the evacuations of the persons attacked and also in a sample of milk supposed to be 
similar to the original toxic milk. The truth of this supposition was confirmed by 
the occurrence at a later date of two similar epidemics, apparently also due to the same 
bacillus. 
Meanwhile it was discovered that the organism in question has a very wide 
distribution, is commonly present in the air and in dust, and is frequently consumed 
in food without producing diarrhoea. 
Again, it has been proved that enteritidis occurs in the evacuations from 
chronic diarrhoea, from diarrhoea secondary to other diseases, and from healthy 
individuals ; it is in fact a normal inhabitant of the human intestines, and 
consequently its presence in the evacuations obtained in certain epidemics has no 
special significance. 
But, as Klein pointed out, the bacillus of Gaertner, bacillus proteus vulgaris 
and streptococcus pyogenes, although also normal inhabitants of the intestine, may 
under certain unknown conditions set up violent diarrhoea.* The value of this 
analogy is considerably lessened, because it is highly probable, if not actually 
demonstrated, that cultures of these organisms are much more virulent to animals 
when producing diarrhoea than when they are quiescent ; whereas, the spores of 
enteritidis, obtained from normal or diarrhoeal evacuations, are equally virulent. 
I believe it is impossible to demonstrate the causal relationship between 
bacillus enteritidis and epidemic diarrhoea by isolating it from the evacuations and 
from food, or by testing its virulence upon guinea pigs. 
Klein, however, records that the swollen lymphoid follicles in the intestine 
of a fatal case of cholera nostras contained, on microscopical examination, in almost 
pure culture, an organism ' morphologically like ' bacillus enteritidis. f 
So it is important to ascertain whether enteritidis sporogenes is constantly 
present in the inflamed intestinal walls of those who have presumably died from its 
activity, making sure that its presence is not the result of post-mortem invasion. 
Again, does the serum of patients suffering from epidemic diarrhoea exert 
any agglutinating action upon enteritidis bacilli ? 
In conclusion, I submit, there is at present no satisfactory evidence that 
bacillus enteritidis sporogenes is a cause of acute, or of epidemic diarrhoea. 
* Medical Officer's Report, Local Government Board, 1898-91). p. 332, 336. 
t Medical Officers Report, Local Government Board, 1897-98, p. 283. 
