SECTION VI. 



LACTIC FERMENTATION AND ALLIED 

 DECOMPOSITIONS. 



CHAPTER XXL 



GENERAL CHARACTERISTICS. 



134. Discovery of the Lactic Acid Bacteria. 



IN chemical text-books acetic acid is generally characterised as 

 being the first acid known to man. This assumption cannot, 

 however, be considered as probable, since, in order to obtain acetic 

 acid, the previous preparation of alcoholic liquids is necessary, 

 and the human race in its earliest stage of civilisation, viz., nomadic 

 life, would hardly have attained that skill the production of 

 wine and vinegar, even in the most primitive fashion, presuppos- 

 ing a settled mode of existence. On the other hand, the flock- 

 owning nomadic races must, at a very early period, have noticed 

 that the milk supplied by their animals very quickly underwent 

 alteration, and turned sour when left to itself. Lactic acid must 

 therefore be regarded as the earliest acid known to man, though 

 not in a pure condition, since that condition necessitates the em- 

 ployment of methods for removing all the other constituents of 

 the milk. This result was first accomplished by the Germano- 

 Swede Scheele in 1780. The earliest complete chemical investiga- 

 tion of the souring of milk was instituted in 1833 by PELOUZE and 

 GAY-LUSSAC (I.), but from that date fully twenty-five years elapsed 

 before the knowledge that this process is a manifestation of vital 

 activity on the part of sundry micro-organisms assumed definite 

 shape. It is true that already in 1701 Andry had noticed that 

 sour milk contained such organised microcosms. Nevertheless, 

 this observation remained at first as unproductive, as regards the 

 comprehension of the question, as did also the labours of sundry 

 other subsequent workers. Among these mention may be made 

 of Blondeau, who in 1847 nia de a microscopic examination of milk 

 and distinguished therein two types of micro-organisms : the one 

 (which he named Torula) was a yeast-like plant; the other, a 

 mould fungus, which he assigned to Penicillium and held to be 

 the cause of lactic fermentation. 



