THE CHARACTERISTICS OF CERTAIN FECAL BACTERIA 
AS SHOWN BY THE LITTLE PLATE METHOD. 
Ola E. Johnston and William D. Frost 
(From the Department of Agricultural Bacteriology, University of Wisconsin, 
Madison, Wisconsin.) 
In another paper we propose to discuss the ‘^Use of the Little 
Plate Method for the Bacteriological Analysis of Feces.” Here 
we describe and illustrate by means of photomicrographs the most 
commonly occurring colonies in the feces of infants, guinea pigs, 
puppies and rats. 
Infants. The ages of the infants studied ranged from three 
days to eleven months. They were all breast fed except one. 
Little plates made from the feces of these infants always showed 
the presence of many diplococci. These organisms varied in 
diameter from 0.6-0.8 microns, although occasionally smaller ones 
were found even down to 0.3 microns. Frequently these units 
grouped themselves in short chains. Some plates contained almost 
pure cultures of diplococci. 
Usually colonies of staphylococci occurred in about the same 
numbers as the diplococci. Besides the irregular grouping, a few 
in tetrads and chains were found. The individual cells were about 
the same size as the streptococci or perhaps more frequently a 
little smaller. 
With one exception all of the infant feces showed the presence 
of as many rods as diplococci or staphylococci. These bacilli were 
either Gram positive spore-bearers or Gram negative non-spore 
bearing rods. They were from 0.5 to 0.8 microns wide and from 
1.0 to 3.5 microns long but most frequently about 1.5 microns. 
Comparing these colonies with the colonies obtained by making 
little plates of pure cultures we have identified the following: 
B.acidophilusy B.alholactis, B.bifidus, B.cereuSy Staph.albus{°l), 
and Strep.lacticus. See figs. 1, 2, 3, 6, 11, 12, 13, 15, 16 and 19. 
Guinea pigs. The fecal flora of fourteen guinea pigs was 
studied by this method. 
