22 THE STOCKFEEDER'S COMPANION 



These ferments are conveniently divided into two 

 classes, viz., organised and unorganised ; and as they 

 play such an important part in agriculture, a general 

 account of their action will be given. 



Organised Ferments are produced by the activity 

 of bacteria, which usually act as " oxidisers " when they 

 attack carbohydrate substances. Common examples 

 may be recalled, such as the souring of milk by the lactic 

 acid bacteria, which change the milk sugar into lactic 

 acid. Various alcoholic drinks derive their alcohol from 

 sugar, which on fermentation with yeast yields alcohol. 

 In the alimentary canal certain bacteria are found which 

 attack and break down the fibrous part of food as it 

 passes through the animal body, with the result that 

 some of the fibre is digested. 



The action of these organised ferments, which are 

 dependent on the existence of bacteria for their forma- 

 tion, can only proceed to ferment food materials as long 

 as there is a supply of air (aerobic), and moisture, as well 

 as a suitable temperature. If air were precluded, or the 

 food desiccated (dried) or refrigerated, this would prevent 

 the multiplication of bacteria, and the production of 

 these organised ferments would come to a standstill. 



Certain organised ferments attack nitrogenous 

 substances, with the production of nauseous gases. If 

 such fermentation takes place in the animal body, as by 

 pathogenic germs, it would cause considerable disturb- 

 ance in the system. 



The "Unorganised" Ferments, or enzymes, are 

 chemical substances which, unlike the organised 

 ferments, are not dependent on the presence of 

 bacteria. A remarkable feature of them is that they 

 appear to have almost an unlimited power of converting 

 nutrient substances into a form in which they are avail- 



