482 



JAMES M. SHERMAN 



forty-eight hours incubation at 37°C. A hand glass with a 

 magnification of three and one-half diameters was used in count- 

 ing the plates made with plain agar, but the lactose agar plates 

 were counted with the naked eye. 



For the comparison of the size of colonies which developed on 

 plain and lactose agars the plates were incubated forty-eight 

 hours at 37 °C. and measurements made by means of a com- 

 pound microscope and eyepiece micrometer which gave a mag- 

 nification of fifty diameters. 



QUANTITATIVE BACTERIAL ANALYSIS 



In table 1 are given the results obtained from eighteen samples 

 of raw market milk when plated on plain and on lactose agars. 

 Among these milks were samples representing all kinds of milk 

 from a very good to a very low-grade type. 



TABLE 1 



Number of bacteria on plain and lactose agars 



Raw Milk 



