318 SOUR-MILK BEVERAGES AND FOODS 



ducts on account of their supposed dietetic and 

 remedial value. 



Several hardy, long-lived races in different parts of 

 Eastern Europe and Western Asia consume considerable 

 quantities of fermented milk, and it has been assumed 

 that their freedom from disease and longevity may be 

 directly connected with the use of this article of diet. 

 In the intestinal tract of man, especially in the colon, 

 putrefactive bacteria are abundant. Here they carry 

 on their work of decomposition and give rise to indole, 

 skatole and other foul-smelling, poisonous compounds. 

 According to Metschnikoff these are absorbed- into the 

 system and bring about premature old age. 



With a view of checking or reducing such intestinal 

 auto-intoxication and changing the bacterial flora of the 

 colon, he has recommended the introduction of the lactic 

 acid organisms through the medium of sour milk. 



As it is not safe to consume spontaneously-soured 

 samples on account of the possible contamination with 

 disease germs, pure cultures of 

 suitable lactic bacteria in sterilized 

 or pasteurized milk are used 

 instead. 



The chief organism employed 

 for this purpose is Bacillus bul- 

 garicus, Heupel, which has been 

 isolated from Joghurt or Maya by 

 Massol, Grigoroff, Luerssen, Kiihn, 

 and others (Fig. 50). 

 Pure cultures are on the market in the form of tabloids 

 and powders, and sold under various names, such as 

 " Lactobacilline," "Joghurt powder," and " Maya ferment." 

 Attempts have also been made to introduce them into 

 chocolate and other bon-bons. 



FIG. 50. The Joghurt bacillus 

 {Bacillus bulgaricus, Heupel). 



