102 DAIRY BACTERIOLOGY 



acid bacteria which are known to thrive there under normal 

 conditions, i.e., the obligate anaerobic rod form Bacterium bifidum 

 (Bacillus bifidus, Tissier) 1 , and various streptococci which the 

 author finds to be related to Streptococcus fceciuw, and glycerinaceus. 

 The common bacteria of sour milk, Sc. lactis and Sc. cremoris, do 

 not thrive in the alimentary canal. If the typical intestinal lactic 

 acid bacteria do not always obtain predominance spontaneously, 

 it will be owing to a faulty diet. If care be taken that the diet 

 contains a far greater proportion of carbohydrates (especially 

 starch, maltose and lactose) than of proteins, then the lactic acid 

 bacteria will always be able to gain the upper hand over the 

 putrefactive bacteria. This result may be achieved by eating 

 more fruit, farinaceous and milk foods than meat, eggs and ripe 

 peas and beans. It should also be borne in mind that man is not 

 purely herbivorous, and can only digest very small amounts of 

 cellulose. The nutrient substances enclosed in voluminous 

 greens are too difficult of access for our digestive system, and are 

 to a great extent carried out into the large intestine, where, 

 together with the cellulose, they set up various anaerobic fermenta- 

 tions. Already, in 1876, Baumann showed that intestinal putre- 

 faction is just as pronounced on a pure vegetarian diet as on a 

 meat diet ; it is most successfully avoided by the rational selection 

 of a mixed diet. 



In the second group of sour milk products alcoholic fermentation 

 plays a far more important part, although the lactose fermenting 

 Saccharomycetes are generally replaced ' by Torulse which are 

 unable to ferment milk sugar directly, but only after it has been 

 hydrolysed to dextrose and galactose by certain lactic acid 

 bacteria. This is the case in Leben ; according to Rest and 

 Khoury 2 , the lactic acid rod forms occurring in this product are 

 only feeble acid producers growing at the ordinary temperature. 

 Olav Johan Olsen Sopp 3 found a similar case of symbiosis in the 

 Norwegian Kaeldermaelk (cellar milk), which is made from boiled 

 milk by inoculating it with a special kind of ropy milk, and 

 keeping it as cold as possible ; on account of the large amounts of 

 lactic acid (up to 2-5 per cent.) and alcohol (about 0-5 per cent.), 

 which are eventually formed, this preparation keeps particularly 

 well and is not even inclined to turn mouldy ; it often forms a 

 substitute for fresh milk when the cows are away from the farms 

 on the mountain pastures, and was formerly very commonly used 

 by the Norwegian peasantry. Kumys is made from mare's milk, 



1 " Recherches sur la flore intestinale norm ale et pathologique du 

 nourisson," Paris, 1900. 



2 " Annales de 1'Institut Pasteur," 1902, p. 65. 



3 " Centralblatt f. Bakteriologie," 2 Abt., 1912, Bd. XXXIII., p. 1. 



