8 
THOMPSON YATES LABORATORIES REPORT 
evidences will remain free from any visible alteration for any length of time. The 
formation of indol and the coagulation of milk seem to result from much more 
complicated reactions, and hence are much more likely to be influenced by external 
conditions. A more exclusive property of B. coli commune than the fermentation of 
glucose is the fermentation of lactose ; this separates it, for example, from B. 
enteritidis (Gartner), which bacillus it closely resembles.* I should add that of the 
84 examples of typical B. coli referred to on page 6, 75 were inoculated into lactose- 
broth, and all that were thus tested showed fermentation of lactose as well as of 
glucose. In the former case the test was made by inoculating with the organisms 
fermentation tubes containing broth, from which all other sugars had been excluded, 
and to which 1 per cent, lactose had been added. Of the three ' coli-like ' organisms, 
mentioned on page 6, the first produced neither acid nor gas in lactose broth in 48 
hours, and thus resembled B. enteritidis .(Gartner), while the two others produced 
acid but no gas in the same medium, even after 12 days. 
Except for the three cases already noted, the B. coli isolated have always 
proved to be typical. The other organisms appearing upon the carbolized agar plates 
could easily be distinguished from B. coli commune. Out of 183 such organisms 
which were isolated, 1 63 were sharply marked off by such unmistakable characteristics, 
as spore-bearing or a coccus form, while the remaining 20 were unlike, though in a less 
noticeable manner. Thus, with a few exceptions, such as those noted above, I have 
not come across examples of the ' coli-like ' organisms often described and said to 
have been found widespread in nature. It may be that this medium inhibits their 
growth. 
Three plates were always poured, and the mean of the three countings was 
taken for the result ; in most cases fairly concordant numbers were obtained (see 
Table lla, which contains the results of a few enumerations taken at random). 
* H. E. Durham. Trans. Path. Soc, Lomlon, 1899, p. 262. 
