ix BACTERIA IN ICE CREAM 125 



(3) Keep the plates at the ordinary temperature, count 

 the colonies, and work them up in the ordinary manner, 

 both microscopically and by means of subcultures in 

 gelatine. 



(b) Examination for typhoid bacilli and the Bacterium coli 

 commune. 



(1) If it is desirable to test ice cream for typhoid 

 bacilli or the Bacterium coli commune, a large quantity of 

 sterile water must be added, for otherwise the plates will 

 be over-grown. 



(2) Work these up in the same manner as described on 

 p. 106. 



The Bacterium coli commune is frequently found in 

 ordinary street ices. 



