44 INFECTIONS OF THE DIGESTIVE TRACT 



The B. putrificus of Bienstock can sometimes be ob- 

 tained from the nursling's intestine by employing a 



which has been inoculated from the simple form of bifidus con- 

 stitutes the best evidence of close relationship of these varieties. 

 In lactose-bouillon fermentation tubes which have been inoculated 

 from the faeces of nurslings one finds in the sediment large numbers 

 of the bifid form of B. bifidus, after incubation for twenty-four hours. 



In anaerobic sugar-agar plates made from the faeces of a 

 human nursling, one finds colonies which develop before those 

 made up of the bifidus type, especially colonies of Staphylo coccus 

 pyogenes albus (which sometimes grow luxuriantly on the surface), 

 and at times one finds varieties of streptococci. An opaque, 

 white, rumpled layer may be seen on aerobic plates made from 

 the first dilutions of the faecal material, which shows itself, under 

 the microscope, to be made up of bacilli possessing motility which 

 on further study prove to be the common potato bacilli (B. mesen- 

 tericus vulgatus, Fliigge). 



In the study of the bacterial flora of the intestinal tract (es- 

 pecially in its lowest portions, colon, sigmoid, and rectum) the 

 routine employment of pasteurization at 80 C. for fifteen or twenty 

 minutes previous to making aerobic and anaerobic plates, is of 

 much value. Most vegetative forms of bacteria present in the 

 human intestine are killed by this exposure to heat, and only 

 those races survive which can form spores and have done so. 

 The application of this procedure is important both in the study 

 of physiological conditions and for the detection of pathological 

 peculiarities of the intestinal flora. On employing this method 

 in the study of the intestinal flora of nurslings, it is found that by 

 the use of suitable culture media, several forms of spore-bearing 

 bacteria are present as regular or almost regular inhabitants of 

 the lower intestine. 



Among the microorganisms which are brought to notice by 

 these methods is a variety which makes on agar small, cottony 

 colonies, of somewhat indefinite outline, giving rise to small gas- 

 production which may cause slight rents in the medium. These 

 colonies consist of Gram-positive bacilli, often colored only in places 

 by the dyestuff, which sometimes carry a knob at one end, which 

 can, in certain instances, be shown to be spores. These spore-bear- 

 ing bacilli are to be regarded as identical with the headlet bacteria 

 already mentioned, and are thus the representatives of the resistant 



