28 vSTORRS AGRICULTURAL EXPERIMENT STATION. 



one which is present frequently to the extent of more than 90 

 per cent, in ripened cream. The source of this organism has 

 been shown by Burr* to be commonly outside of the cow, and 

 probably the dirt and dust in the air of the stable. It is 

 present, as may be seen in all the following tables, in small 

 numbers in fresh milk, and then with almost absolute uni- 

 formity it increases in numbers and percentage until the end 

 of the experiments. 



D. acidi ladici II. This is a species which we have found 

 quite common in this region, though less common than the 

 previous. In many respects it resembles the preceding organ- 

 ism and may possibly be a variety of the same. We have 

 found that in most cases it is not observable in the samples of 

 fresh milk but makes its appearance in the later stages of 

 souring. 



B. ladis aerogencs. As indicated above, the organisms in- 

 cluded under this title in the tables may be not only B. aero- 

 genes but also B. colt, should it chance to be present, inasmuch 

 as these species are not readil}^ differentiated upon the gelatin 

 plates. We are convinced by the study of large numbers of 

 colonies, however, that in the vast majority of cases the organ- 

 isms tabulated here are B. aerogenes, and only a comparatively 

 small proportion consist of B. coli. 



The Streptococcus we have found with absolute uniformity in 

 all samples of milk which we have studied. It is usually ver}" 

 abundant, though sometimes in small numbers only. It ap- 

 parently comes in many cases from the udder of the cow. Its 

 colony on the litmus gelatin has already been described. 



Sarcina lutea is found almost universally in samples which 

 we have studied. We have also found a Sarcina which in the 

 early stages appears to be different from it, but later develops 

 into a somewhat similar colony; this we have tabulated as Sar- 

 cina II., regarding it as a different species from the first. 



The column headed rapid liqiiefiers is made up of probably 

 two and possibly three species. These are bacteria which grow 

 W'ith extraordinar)' rapidit}', and occasionally ma}' completely 

 liquefy a gelatin plate in the course of twenty-four hours and 



*StorrsExpt. Sta. Rept. 1900, p. 66. 



