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March 1922


Arch Intern Med (Chic). 1922;29(3):357-367. doi:10.1001/archinte.1922.00110030082005

Bacillus acidophilus was first observed and described in 1900 by Moro.1 It is a rather large gram-positive bacterium which is quite pleomorphic and which in many respects resembles Massol's Bacillus bulgaricus and Tissier's Bacillus bifidus. It was claimed by Moro to be the chief inhabitant of the intestine of infants that subsist entirely on mother's milk. This assertion was disputed by Tissier2 who protested that B. bifidus holds the place of prime importance. B. acidophilus and B. bifidus are now known to constitute the main flora of the breast-fed child, the latter being, perhaps, the more prominent of the two. As the diet changes and becomes more and more complex, there is a corresponding change in the kinds and relative numbers of intestinal bacteria, until finally the intestinal population assumes the character of that of the ordinary adult. B. acidophilus and B. bifidus gradually disappear to such an extent that