CHAPTEE XI. 



MICKO-ORGANISMS OTHER THAN BACTERIA- 

 FERMENTATION, ETC. 



The yeasts, moulds, algse and protozoa : their method of growth, 

 classification, mode of occurrence, chief species, etc. — The examina- 

 tion of yeasts— Fermentation and ferments — Fermentation hy yeasts 

 — High and low fermentation — Fermentation by moulds and 

 bacteria — The acetic fermentation of alcohol, the nitrification of 

 ammonia, the ammoniacal fermentation of urea, the lactic and 

 butyric acid ferments — Mixed fermentations — The unorganised 

 ferments, or enzymes — The diastatic, peptic, rennet and pancreatic 

 ferments. 



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 

 making, etc. Most of the above organisms are harmless 

 saprophytes, while others are of pathological importance, 

 as being associated with disease. 



