and other articles of consumption. Of such importance 

 indeed has a knowledge of these organisms become to 

 brewers, that many of them keep a well-paid analytical 

 chemist on the premises, whose duty it is to supeirintend 

 the working of the wort, and take care that no deleterious 

 organism is allowed to grow in it. 



The Schizomycetes or Bacteria act also by a process 

 akin to fermentation, but they have no particular affection 

 for sugar, for they principally attack dead organic matter. 

 In extracting its favourite nourishment from its food each 

 one, much as do the yeasts, breaks it up into its elements, 

 and produces a secretion peculiar to itself, which may be 

 mere colouring matter, some acrid or stinking product, or 

 some poison inimical to the growth of itself or species, and 

 deadly to animals or the human race. Indeed the Bac- 

 teria are credited with being the causes of most of the 

 diseases which human flesh is heir to ; and it has been 

 proved that they are the causes of suppuration [i.e., of the 

 formation of matter), in wounds, so that the use of antisep- 

 tics, to prevent their growth, is now pretty generall}' adopted 

 by surgeons after operations. 



The Hyphomycetes or moulds, act in a similar way; and 

 although they are of a somewhat more complex structure, 

 appear to finish off the scavenging which the others began. 

 There is no doubt that some of them also are the causes 

 of disease. 



Now, as regards the nutriment of Micro-organisms, they 

 require substances containing nitrogen, carbon, certain 

 mineral salts, and water. Most of them flourish best in 

 oxygen, i.e., in the air, and are hence called Aerobics. Some 

 grow best out of it and are called Anaerobies. 



They may be cultivated artificially in many ways. Some 

 grow well on potatoes, and the colour producing bacteria 

 make very pretty objects on them. Their presence in the 

 air may be easily shewn by this means. — Take two slices of 

 newly boiled potato, cut with a knife which has been heated 

 to redness, put one on a plate under a glass bell-jar at once. 



