LEO F. RETTGER 641 



Moro' for a while disputed Tissier's claim, and believed that his Lactobacillus 

 acidophilus, which is apparently the same as the "Siiureliebender Bacillus" of Finkel- 

 stein, is the dominant species. Both the Tissier and the Moro organisms, which are 

 closely related to each other in many respects, are prominent in nurslings' stools. In 

 the change from mother's to cow's milk, L. acidophilus tends to displace the Tissier 

 bacillus. As the child grows older and the diet becomes more varied (milk and eggs, 

 for example) the flora changes from the simple to one that is more complex; and as 

 the daily food more nearly approaches in kind that of the ordinary adult a more or 

 less definite, varied flora becomes established, in which the aciduric organisms of in- 

 fancy, L. bijidus and L. acidophilus, have all but completely disappeared, in so far as 

 microscopic and cultural observations will determine, and Bact. coli as a rule plays a 

 very dominant role. 



Tissier noted the presence of the following intestinal organisms in a five-year-old 

 child: L. bifidus, L. acidophilus, Enterococcus {Strept. fee alls), Bad. coli, B. exilis, and 

 B. rodella III. These he regarded as the constant, fundamental flora. Besides these he 

 observed the following variable, secondary flora: B. perfringens (CI. welchii), Staph, 

 parvulus, B. Jundnliformis, B. capillosus, B. ventriosus, Coccobac. praecutus and ovi- 

 formis, Diplococ. arbiculus, and different yeasts. 



It is impossible to identify some of the secondary organisms of Tissier with known 

 species today, and their names are perhaps of little significance. It must be conceded, 

 too, that our knowledge regarding the biological entities and relationships of the mi- 

 crobic population of the intestine is stifl far from complete. 



The following groups of organisms are known to be present in the intestine of the 

 ordinary adult: 



1. Coli-aerogenes group 4. Anaerobes 7. Spirilla and spirochetes 



2. Aciduric types 5. Proteus group 8. Yeasts 



3. Micrococci 6. Subtilis group 9. Molds 



THE COLI-AEROGENES GROUP 



Bact. aerogenes is comparatively rare, while Bact. coli proper is present in large 

 numbers in the intestine of man and the lower animals. In fact, very few species of 

 animals appear not to be natural carriers of this organism. It is, however, seemingly 

 foreign to the intestine of fishes, according to Hunter^ and others, and of shellfish, and 

 is found in them only when they occupy waters which contain this organism as the 

 result of pollution by man and the lower animals. 



THE ACmURIC GROUP 



This is represented by L. bijidus and L. acidophilus, both of which are character- 

 istically intestinal organisms. They resemble each other in that they are gram posi- 

 tive, produce and tolerate appreciable amounts of lactic acid, and have high energy 

 requirements. L. bifidus was so called because of its tendency to branch or bifurcate. 

 In this respect it differs from L. acidophilus, which reveals branching forms but rarely, 

 in spite of certain claims to the contrary. The two differ also in that L. bifidus is mi- 



' Moro, O.: Jahrb.f. Kinderh., 52, 38. 1900; Wien. klin. Wchnschr., 13, 114. 1900. 

 - Hunter, A. C: /. Bad., s, 353. 1920. 



