108 PHARMACEUTICAL BACTERIOLOGY. 



3. The Lactic Acid Microbe and Kefir Preparation. 



Within recent years the subject of intestinal digestion and the relation- 

 ship of intestinal microbes to digestion and longevity has received much 

 attention. Metchnikoff declares that the early senile cell changes in the 

 body are due to the repeated or chronic autointoxications brought about 

 by certain noxious intestinal ferments of bacterial origin which are absorbed 

 into the circulation. Some of these bacteria, especially those found in the 

 small intestines, are beneficial, secreting enzymes which aid digestion, but 

 the enormous quantity of microbes active in the lower large intestine are for 

 the most part injurious, producing putrefactive changes, liberating toxins 

 which when absorbed into the system in sufficient quantity produce the 

 symptoms of ptomaine poisoning. 



In order to combat these objectionable bacterial activities, it is necessary 

 to regulate the bacterial development in the large intestine. Lactic acid has 

 long been known as an efficient remedy in the treatment of various intestinal 

 disorders. It is known that the poor of certain European countries who 

 live largely on potatoes and clabbered or thick milk are notably free from 

 intestinal disorders and are remarkably long-lived. It is known that pickles, 

 sauerkraut and sour milk are excellent bowel regulators, in spite of the fact 

 that these foods, the former two in particular, are well-nigh indigestible and 

 have little food value. The Arabians have long used koumys as a healthful, 

 life-prolonging article of diet. To this class of foods also belongs the Bul- 

 garian yoghurt and the Egyptian raib. 



The ferments of koumys, kefir, yoghurt and raib resemble each other in 

 that they are mixed, consisting of several lactic-acid microbes or organisms 

 and yeast organisms. These foods or drinks therefore contain lactic acid 

 and a small amount of alcohol. 



As soon as it was determined experimentally that the beneficent action of 

 sour milk, thick or clabbered milk and the above-named special preparations 

 was largely due to the lactic acid formed by specific microbes, efforts were 

 made to isolate these organisms in pure culture and to induce them to act 

 in sterile or pure milk. This has been done, and there are now upon the 

 European and American market several patented preparations consisting 

 of the lactic acid bacillus. 



Our knowledge of the relative importance of the several organisms which 

 are said to produce the fermentative changes in the milk is as yet incom- 

 plete. Bacteriologists have thus far not succeeded in disclosing all of 

 nature's secret processes involved. It is supposed that the microbe of 

 Bulgarian sour milk, the Bacillus bulgaricus, is the most vigorous and active 

 of all organisms concerned in the lactic-acid fermentation of milk. 



It is not definitely determined whether or not the fermentations of milk 



