BACILLUS LACTIS 217 



In Grape and Milk Sugar Bouillon the growth is luxuriant, the media 

 becoming strongly acid without the production of gas. 



To obtain pure culture of the organism from sour milk proceed as 

 follows : 



1 . Melt three tubes of gelatine in the water-bath at 30 C. 



2. Put some CaCO 3 in a clean tube, add a little water, sterilize in 

 the steamer, or boil over the Bunsen flame. 



3. Inoculate the first or original tubes with three platinum loops of 

 milk, and reduce in the usual manner, using five platinum loops of milk. 

 Mix the milk and gelatine thoroughly. 



4. Put a few drops of the solution of CaCO 3 in three sterile Petri- 

 dishes, pour the inoculated gelatine on the CaCO 3 , and see that they 

 are thoroughly commingled. 



After development each acid-forming colony will be found surrounded 

 by a transparent field. 



BACILLUS LACTIS (FLUGGE). 



Found in bitter milk. Flugge isolated eleven different varieties, 

 which all belong to the group of hay bacilli. They possess the power 

 of peptonising the casein of the milk, whereby it acquires a bitter taste. 

 A few of the varieties produce toxic substances which, when given to 

 young dogs per os, caused diarrhoea, muscular weakness, and falling of 

 the temperature. They form very resistant spores, which are not 

 destroyed by several hours' cooking. It is on account of these spores 

 that the sterilization of milk is so difficult. If improperly sterilized milk 

 is placed at a high temperature, the spores germinate, the above- 

 mentioned poisonous substances being formed. Some authors consider 

 that these substances may be the cause of summer diarrhoea in children. 



The morphological characters of these eleven species of bacteria are 

 similar to those of the Bacillus subtilis (see page 210). They are all motile 

 rods of various lengths, and all liquefy gelatine media. (See also Bacillus 

 Anaerobius (Flugge), 2, 3, and 4, page 214). 



BACILLUS LACTIS INOCUUS. 



Found in the faeces of infants and in milk ; short, non-motile 

 rods. In the animal body it forms capsules. 



Biological Characters. Aerobic. 



On Gelatine Plates white, round, non-liquefying colonies develop. 



On Potatoes a brownish coating. 



Milk is not changed. In grape sugar agar no gas is formed. Indol 

 is not formed. 



Pathogenic only in very large doses. 



