GROWTH OF BACTERIA IN NORMAL MILK. 35 



8. The milk showed an exceptionally large number of mis- 

 cellaneous bacteria, as will be seen from Table 3. It will also 

 be noticed that these miscellaneous types must play a very 

 small part in the changes that occur in milk. They were 

 present only in small numbers at the start and in milk that 

 was six hours old, and then disappeared, only one species in- 

 creasing in numbers up to the close of the experiment. The 

 rest were indistinguishable on the last series of plates. 



9. The number of undetermined bacteria in these plates 

 was somewhat variable but not very large. It should be no- 

 ticed, however, that the large number of liquefiers which were 

 present at fourteen and nineteen hours made a sharp differen- 

 tiation of B. acidi ladici and the common Streptococcus difficult, 

 and probably explains the slight irregularities shown in the 

 two tests. 



10. It is to be noticed finally that the total number of bacte- 

 ria at the end of the experiment was very small. This is shown 

 by a comparison of the numbers given in Table 3 with those in 

 Table 7; it will be seen that whereas in the later experiment 

 the number at the start was 8,000 and increased in twenty- 

 seven hours to 3,000,000, in the present experiment, as shown 

 by Table 3, the number at the start was 13,000 but at the end 

 of twenty-four hours only 716,000. This is simply one in- 

 stance of what we have found to be a general rule, that the 

 number of bacteria at the start gives very little indication of 

 the number that there may be present after twenty-four hours 

 even under similar conditions. 



