102 MODERN DAIRY PRACTICE. 



colored, somewhat viscous fluid, which would hardly remind 

 one of milk. It is further characteristic for the culture of 

 these bacteria in milk that a lively generation of gas often 

 takes place in the substratum. Carbonic acid seems to be 

 the main gas generated. I have also observed a smell 

 suggesting sulphuretted hydrogen. The presence of small 

 quantities of alcohol and acetic acid may further be shown 

 by distillation of the milk. 



Among the organisms belonging to this family I have 

 only observed two varieties in Finnish milk the one very 

 thin and long, the other thicker and shorter. Neither 

 seem to shun daylight particularly ; they are both killed by 

 a single rapid heating of the substratum to 158 F. (70 C.). 

 They seem to be found almost regularly in stringy milk; * 

 they doubtless play a part in the formation of this milk, 

 although they also seem to be assisted by others, e.g., of a 

 lactic-acid bacterium appearing as streptococcus; the latter 

 does not produce volatile acids, as is the case with other 

 lactic-acid bacteria. 



Za. Bacteria Causing Coagulation of the Casein. 

 Three different varieties found in Finnish milk are in- 

 cluded in this subdivision. Of this number only one, how- 

 ever, calls for special mention, since the other two seem to 

 be comparatively rare. The third one is very common, and 

 in my investigations has been found to appear in particu- 

 larly large numbers in milk which had come in contact 

 with manure-particles, etc. It is a short bacillus 

 (1.5 X .5 /*), often thinner in the middle and with round- 

 ed ends. Its power of locomotion is very pronounced. 

 Thread-formed runners from the small colonies are no- 



* See " Saprophytic Micro-organisms in Cows' Milk," p. 27. 



