42 MICROBES AND TOXINS 



is in others itself a putrefying organism. Kolbriigge's opinion 

 can no longer be maintained that the B. colt is the beneficent 

 bacterium far excellence, growing in the appendix as in a sort of 

 hot-house put specially there by Providence ! 



The antagonism is chiefly between the B. perfringens of 

 Welch and the B. bifidus discovered by Tissier in the normal 

 flora of the healthy breast-fed infant. 



There is a general antagonism between the simple saccharo- 

 lytic bacteria which produce acid from starches and sugars 

 and the simple proteolytic bacteria which carry the digestion of 

 meat to the stage of indol, skatol, phenol, and ammoniacal 

 salts. When the bacteria which oppose each other are both 

 proteolytic and saccharolytic (hence called mixed ferments), 

 those which produce the most acid inhibit those which produce 

 less. 



For example, the enterococcus is inhibited by an acidity of 

 2'45 per looo ; the B. perfringens at i"6o per looo ; the B. 

 acidi paralactici at 5'39 ; the B. bifidus at 4'9o. The two 

 last are evidently successful antagonists of the B. perfringens. 



The facts established by Bienstock aiid by Tissier and 

 Martelly may be expressed as the following law : in media 

 containing protein along with more than lo per looo of sugar, 

 a " mixed ferment " can arrest the development and the 

 action of a simple ferment, whereas a strong mixed ferment 

 (i.e., a strong acid producer) can inhibit a weaker. These 

 inhibiting actions are entirely due to the quantity of acid 

 which the bacteria produce in the course of their consumption 

 of the carbohydrates. 



Principles of Intestinal Bacteriotherapy. — 

 Metchnikoff s experiments on microbial associations in cholera 

 contain the germ of a method of treatment which consists in 

 using inhibiting bacteria. The experiments of Bienstock 

 and Tissier indicate that the saccharolytic bacteria form a 

 natural obstacle to the action of the putrefying microbes. 

 The idea of a bacteriotherapy had already been formulated by 

 the well-known children's physician, Escherich, practically in 

 the following terms : " It is necessary to employ the ' acid 



