ORGANISED FERMENTS 13 



processes a mode of reduction usually effected by the 

 organised ferments. 



The organised ferments, which are the causes of putrefac- 

 tion and of various diseases, have been classified as 



1. Yeasts, or sprouting fungi, which consist of ovoid cells, 

 multiplying by budding, are represented by the torula cere- 

 visise, mycoderma vini, and, according to most authorities, 

 also include the aphthous patches of thrush found in the 

 mouth of young animals. 



2. Moulds, or filamentous fungi, occur in threads, which 

 are agglomerated into masses or tufts, multiplying by 

 budding and formation of spores, and exemplified by the 

 common moulds which appear on moist objects, and by 

 those which cause such skin diseases as favus and ringworm. 



3. Bacteria, Microbes, or Schizomycetes, are the lowest 

 forms of vegetable life, but the most widely distributed, in 

 air, earth, and water. They consist of round, oval, or 

 cylindrical cells, so minute that they can only be examined 

 with high powers of the microscope. They multiply chiefly 

 by division, occasionally by spore formation. Their multi- 

 plication is effected with enormous rapidity, a single indi- 

 vidual cell sometimes producing a million in twenty-four 

 hours. Some are fixed, others are motile. For their 

 formation and growth they require organic matter, moisture, 

 salts, and a moderate temperature ; some, further, need 

 oxygen ; some thrive without it. They speedily exhaust 

 the nutriment obtainable from the substance on which they 

 grow, or form in it matters inimical to their life ; but where 

 one species languishes and perishes, others frequently spring 

 up and flourish. 



Bacteria are divided into two groups (1) Non-pathogenic 

 or saphrophytic. Many of these feed and live on dead animal 

 or vegetable matter, and their great function is the conver- 

 sion of complex into simpler forms. They are exemplified 

 by the bacillus of hay infusion, the bacterium termo found 

 in all putrid fluids, and the bacilli developing the saccharine 

 and lactic fermentations. (2) Pathogenic or parasitic 

 bacteria live on or within the bodies of living plants or 

 animals, and when in large numbers interfere with nutrition 

 and cause disease. Their pathogenic power is proved 



