GASTRO-INTESTINAL FLORA OF NORMAL INFANTS 0)65 
motile, non-sponilating rod-shaped l)acilliis, wliich is found in the 
alimentary tract of artificially-fed children and adolescents quite fre- 
quently. It possesses the power of decomposing urea rapidly into 
ammonia and it is the causative organism of a form of dermatitis 
(Jacquet dermatitis^) caused by the fermentation of urea in the napkins 
of young children. 
The microbe is without action upon sugars, it fails to liquefy gelatin 
and grows well upon ordinary cultural media. ]\Iilk is rendered 
slightly alkaline. The addition of urea to media is followed by an 
increased alkalinity, and the liberation of much ammonia. 
The organism is not pathogenic. 
Escherich- has emphasized the very significant fact that putrefactive 
(proteolytic) bacteria are uncommon in the dejecta of normal nurs- 
lings; there is little or no evidence of the development of these organ- 
isms in the intestinal tract during this stage. The putrefactive 
bacteria, as a rule, do not develop in an acid medium in competition 
with organisms like B. bifidus and other acidogenic types which dom- 
inate the alimentary canal of the normal nursling. 
Distribution of the Intestinal Flora of the Normal NursUng.— The 
principal portal of entry of the intestinal bacteria is the mouth. There 
is no doubt that a great variety of organisms may from time to time 
enter this atrium, including not only the ordinary organisms of the 
nurslings' environment, but pathogenic bacteria as well. A majority 
of these pass to the stomach, and they may pass to the intestinal 
tract. The flora of the mouth and stomach are not well known, but 
they appear to be of relatively slight importance as a rule. Those 
adventitious organisms which pass from the stomach to the duo- 
denum rarely appear to gain a foothold there, or at lower levels of 
the intestines. 
The duodenal flora, which in health is composed chiefly of coccal 
forms of the Micrococcus ovalis type, is most numerous during those 
periods when the food is passing through; during interdigestive periods 
there appear to be relatively few bacteria at this level. From the 
jejunum to the ileocecal valve, members of the B. lactis aerogenes 
group occur more commonly. B. coli and other members of the colon 
group are most numerous at the ileocecal valve and the cecum, and B. 
bifidus or similar organisms dominate the large intestines from this 
level to the sigmoid flexure. The remainder of the large intestine to 
the rectum is somewhat sparsely populated with living bacteria, partly 
because the fecal mass is relatively desiccated by the absorption of 
water, partly because of the accumulation of waste products of bacterial 
activity— principally acids resulting from fermentation of lactose, 
formed higher up in the tract— which inhibit the development of 
bacteria in the lower levels.^ 
' Rev. Mens. d. Mai. d. I'enf., 1886, 4, 208. 
2 Loc. cit. 
3 Kendall: .Jour. Med. Res., 1911, 25, 117 et seq. 
