46 STORRS AGRICULTURAL EXPERIMENT STATION. 



It is possible that the experiment of January 15 should be 

 excluded from our series, the excessive number of liquefiers 

 interfering so materially with the proper differentiation of spe- 

 cies that the column of undetermined is an extremely large 

 one. At all events, too much value must not be placed upon 

 this experiment, but we have included these tables for the pur- 

 pose of showing, if nothing else, the variations and the diffi- 

 culties of determining the strict differentiation of species under 

 these conditions. 



Further tables giving the growth of bacteria at 20° C. will 

 be found in the later sections of this paper, but since they do 

 not materially change the facts already given it will be well to 

 summarize at this point the results obtained. 



GENERAL SUMMARY. 



If we compare the foregoing experiments we shall notice the 

 following facts: 



1. There are considerable irregularities as to both total 

 numbers and increase of different species under what seem to 

 be identical conditions. There is in all cases a constant in- 

 crease in the total numbers of bacteria of each of the species 

 given in the first eight columns of our tables. The miscellane- 

 ous species are always present in small numbers, but they dis- 

 appear in the later tests in all cases, which means that they 

 have not increased materially during the experiment. 



2. There is in all experiments a constant increase in the 

 percentage of B. acidi ladici. This indeed is the only one of 

 the bacteria found in milk in these samples which shows a 

 constant increase in percentage during the successive tests. 



3. The Streptococcus group is present in all cases in con- 

 siderable abundance, continues to multiply during the first 

 twenty-four hours, and commonly just about holds its own in 

 percentage. This indicates that, as a rule, it multiplies more 

 rapidly than any of the other species except B. acidi lactici. 



4. The two species of Sarcina are universally present in 

 the milk and continue to increase in numbers in all experi- 

 ments, but their percentage generally declines somewhat, so 

 that they are relatively less abundant in twenty-four hours 

 than at the start. 



