2 TRANSFORMATION OF THE INTESTINAL FLORA 



serving as the chief portals of entry for bacteria, the establishment of 

 the characteristic flora of the infant does not take place prior to the 

 administration of food, as was pointed out by Escherich (1885), 

 Tissier (1900) and Moro (1900a). 



According to the substantiated claims of Tissier, his B. bifidus is 

 the predominant organism in the stools of breast-fed infants. In the 

 change from breast- to bottle-feeding B. bifidus is in a large measure 

 replaced by B. acidophilus, as has been claimed by Logan (1914) and 

 others. While cow's milk brings about a less homogeneous flora than 

 mother's milk, there is a large proportionate increase of B. acidophilus, 

 not infrequently to the exclusion of all other organisms. As the child 

 grows older and the artificial feeding becomes more varied, there 

 appears a more and more complex flora which in the course of time 

 resembles that of an adult. Fischer (1903) was the first to call atten- 

 tion to this change. Sittler (1910) and others confirmed the obser- 

 vation. 



The comparatively recent experiments of Cohendy (1912) and 

 Kiister (1913) have for the time at least answered the question first 

 propounded by Pasteur, namely whether intestinal bacteria are neces- 

 sary for the well-being of the host. On the other hand, the enormous 

 numbers of bacteria in the intestine of man and animal have been the 

 subject of numerous researches into methods of quantitative determina- 

 tion. Eberle (1896), Klein (1900) and Hehewerth (1900) employed 

 the direct microscopic count; Winterberg (1898) for the first time 

 made use of the Thoma-Zeiss blood-counting chamber in this connec- 

 tion, while Strasburger (1902) resorted to the gravimetric method, 

 which proved very efficient. Others have by means of the plate culture 

 and other methods estimated the total number of bacteria in feces. 

 Thus, MacNeal, Latzer and Kerr (1909) have estimated the average 

 number of fecal bacteria excreted daily by a normal adult subsisting 

 on an ordinary diet as thirty-three times ten to the twelfth power 

 (33x10^"), and that this number of bacteria is equivalent to 5.34< 

 grams of dried bacteria or 0.585 gram of bacterial nitrogen. Matill 

 and Hawk (1911) place the daily output at 8.27 grams of dried bac- 

 teria, and Sato (1910) at 8.54 grams. Berger and Tsuchiya's (1910) 

 estimate was much lower, namely 3.023. Strasburger calculated that 

 a healthy adult daily excretes about 8 grams of (dried) bacteria, or 128 

 trillions. 



The influence of sterile food on the intestinal population was studied 

 by several investigators. Sucksdorff (1886) and Brotzu (1895) 

 claimed that sterilized food reduces the number of bacteria in the ali- 

 mentary tract. Similar results were obtained by Gilbert and Dominici 

 (1894). However, the researches of Stern (1892), Adrian (1895), 

 Eberle (1896) and Ballner (1904) failed to confirm this assertion. 

 Escherich had shown that the sterilization of the food had little or no 

 influence on the number of intestinal organisms. Hammerl (1897), 



