10 



It is a microbe closely allied to the cholera and the photogenic vibrios. The tyrosinase 

 function is sometimes suddenly lost by unknown influences, but may return in the 

 same stock. Notwithstanding, the species can be considered as fairly constant and 

 remains so for years in the laboratory. 



Beer, poor in extract, colours dark brown when corrupting at the air. This is 

 owing to the presence of a vinegar bacterium, Acetobacter melanogenum, which 

 produces a pigment reminding of caramel from peptome. By the secretion products 

 of A. melanogenum gelatin is as it were tanned and becomes insoluble in boiling 

 water. Perhaps chinon is inferred in this process. 



In natural varieties of the species of microbes, which in all other respects show 

 no difference, the oxidation function in regard to certain substances may be either 

 or not present, but if present it may be very constant in these varieties. 



