GROWTH OF BACTERIA IN NORMAL MILK. 7 1 



4. The species of Sarcina played no part in the changes 

 that must have taken place in this milk. They were present 

 in considerable quantity and moderate percentage at the start, 

 but disappeared from the plates by the fortieth hour, and were 

 therefore present, if at all, only in small numbers. 



5. The liquefiers played little part in the experiment, their 

 numbers remaining practically constant so far as concerns per- 

 centage, though the total number increased with some regu- 

 larity. 



6. The other three miscellaneous species given in the tables 

 either disappeared during the experiments, or became so small 

 in numbers as not to be noticeable in the later tests. 



7. The chief change which occurred in the bacteria in the 

 sample of milk retained at 13° was the extraordinary multi- 

 plication of the Streptococcus group. Beginning somewhere 

 between the thirtieth and the fortieth hour, this bacterium 

 multiplied very rapidly, increasing the total numbers of bac- 

 teria more than tenfold and producing a corresponding de- 

 crease in the percentages of all other species. The other 

 species of bacteria remained without any considerable increase 

 during the whole experiment. 



Expet'iment No. 14.. February 10. — The conditions of this 

 experiment were identical with those of the preceding. The 

 results are shown in the following tables: 



