2.54. INTESTINAL BACTERIA 
the bacterial substance is generally settled, so that most of the clear 
supernatant liquid, of dark brown color, can be directly siphoned off 
without loss of solid matter. The remainder is then transferred to 
contnfuge tubes, centrifugalized, and the remaining clear liquid pipetted 
off. The sediment consists of the bodies of the bacteria, and is trans- 
ferred to a Kjeldahl flask for nitrogen determination. This is the bac- 
terial nitrogen. Where a detefmination of bacterial dry substance is 
desired, the sediment of bacteria is extracted by absolute alcohol and 
ether in succession, transferred to a weighed porcelain crucible, and 
dried at 102° C. constant weight. This dried sample is then used in the 
nitrogen determination. Our procedure differs from that of MacNeal 
in that the bacterial dry matter is not determined. A saving of about 
seven days’ time and of considerable labor is accomplished by this 
omission. 
‘“ Tnasmuch as it has been shown by various investigators that such 
bacteria as are present in the feces contain on the average about 11 per 
cent of nitrogen, the values for bacterial nitrogen as determined by our 
method may conveniently serve as a basis for the calculation of the 
actual output of bacterial substance.” 
EXAMINATION OF Freces FOR Bacituus TyPpHosus 
Lumsden and Stimson’s Method. ‘Place about 5 gms. of the feces 
in a conical glass or other suitable vessel, add about 15 or 20 c.c. of 
sterile physiological salt solution or bouillon and agitate. Let stand 
one-half to one hour either at room temperature or, preferably, at 
incubator temperature (37° C.) in order to permit the heavy particles to 
settle. Deposit one or two drops of the prenatant fluid in the center 
of an Endo plate. With a right-angled glass rod distribute the drop 
over the entire surface of the plate and then rub the rod over the surface 
of a second, third, fourth and fifth Endo plate. By carrying the spreader 
over the surfaces of several plates in this way, one or two of the plates 
will furnish abundant but sufficiently isolated colonies to permit 
‘ fishing.’ 
‘“ After inoculation place the plates inverted in the incubator, leave 
there for twenty to twenty-four hours, and then examine. On the 
plates colonies of typhoid and paratyphoid bacilli will be transparent, 
colorless, dew-drop like and usually from 1 to 2 mm. in diameter; while 
colonies of colon bacilli will be deep red, showing sometimes on the sur- 
face a sheen from precipitation of the fuchsin, and measure usually from 
