CHAPTER XI. 



MICRO-OEGANISMS OTHER THAN BACTERIA- 

 FERMENTATION, ETC. 



The yeasts, moulds and algae : their method of growth, classification, 

 mode of occurrence, chief species, etc. — The examination of yeasts — 

 Fermentation and ferments — Fermentation by yeasts— High and 

 low fermentation — Fermentation by moulds and bacteria — The 

 acetic fermentation of alcohol, the ammoniacal fermentation of urea, 

 the lactic and butyric acid ferments — Mixed fermentations — The 

 unorganised ferments, or enzymes — The proteolytic, amylolytic, 

 inversive and coagulative enzymes of bacterial origin — Putrefaction 

 and oxidation — ^Action of water filter-beds — Nitrification of ammonia 

 — Fixation of atmospheric nitrogen — ' Nitragin ' — Chromogenie 

 bacteria and colouring matters — Colouring matter, B. cyamogenus, 

 B. proddgiosus, B. pyocyaneus, etc. — Phosphorescent Bacteria — 

 Other products of the metabohsm of micro-organisms — The 

 bacteriology of sewage. 



In addition to the bacteria proper are a large number of 

 micro-organisms which, although more highly organised, 

 are very closely related to the bacteria. They are known 

 as yeasts (or saccharomycetes), moulds, algse, and protozoa. 

 There are a great number of varieties of the above organisms, 

 and we cannot attempt to describe even all the most im- 

 portant ones ; but it will answer our purpose to detail a few 

 of the more common kinds, and give the principal features 

 of the different orders. The yeasts are the most important, 

 as they play an important part in our daily life, being the 

 basis of such great industries as brewing, wine and vinegar 



