376 Bacteria in Relation to Country Life 



the others in this connection. Bacterium prodigiosum 

 grows best at about 75 Fahr., and develops readily 

 on bread, boiled vegetables and boiled meat. The red 

 coloration of milk, as due to these organisms, is of minor 

 significance, for it occurs only on milk that is some days 

 old, and then very rarely. The same may be said of 

 other bacterial colorations, such as various shades of 

 yellow and green. 



Bitter milk. So-called bitter milk is another of the 

 milk faults occasionally forced upon the attention of 

 the dairyman. It may develop in pasteurized or ster- 

 ilized milk, and is due then to spore-forming anaerobic 

 ferments. At other times, it may be due to aerobic 

 organisms developing in either raw or boiled milk. 

 The bitter taste thus produced is probably caused by 

 certain decomposition products of the casein. 



Ropy milk. Slimy or ropy milk, as produced by the 

 activities of bacteria, is quite distinct from the ropy or 

 stringy milk that has its origin in diseased udders. 

 When of bacterial origin, the milk fault develops gradu- 

 ally in milk that is in every way normal when freshly 

 drawn. In twelve to thirty hours, the milk becomes 

 viscid and may be drawn out in long threads. 



The list of organisms capable of producing sliminess 

 or ropiness in milk is fairly long. One of them, first 

 isolated by Adametz and called by him Bacillus lactis 

 viscosus, is peculiar in that it can grow well at temper- 

 atures of 45 to 50 Fahr., when the common milk bac- 

 teria are dormant. After ropy milk has once appeared 

 in a vessel of milk, a fruitful source of future trouble is 

 occasioned by careless scalding of the vessel when it is 





