102 The Living Plant 



respiration of the higher plants and typical fermentation. Ideally, 

 in the respiration of the higher plants, the oxygen absorbed and 

 carbon dioxide released are equal in volume, but often they are 

 not. Thus, some kinds of seeds, like Peas, if shut away from 

 oxygen, can release plenty of carbon dioxide without absorbing 

 any oxygen at all; and analysis of the seeds then shows the pres- 

 ence of alcohol. In other words, these Peas, like the Yeast plant, 

 can cause fermentation (though in limited degree) of some of 

 their own substance; and there is no doubt that it represents the 

 form of respiration to which the seeds resort when no oxygen 

 from the air is available. This form of fermentation is called 

 in the Peas, and the other plants which make use of it, anaerobic, 

 or intramolecular, respiration. 



There remain two other forms of fermentation so important 

 as to require a separate treatment. One is decay, or putrefaction, 

 which is really the fermentation of dead plant and animal sub- 

 stances by Bacteria, or germs. Bacteria are plants even smaller 

 and simpler than Yeasts. The products of their respiration and 

 growth are most diverse, including not only carbon dioxide and 

 water but various other gases, some of which possess those very 

 vile odors distinctive of rotting organic matter. When the de- 

 caying substances are complex, e. g., flesh or other proteins, certain 

 Bacteria ferment them to simpler sorts, other kinds to simpler 

 still, and so on, until they are finally reduced, as in ordinary respir- 

 ation, to carbon dioxide and water, and such other elemental 

 substances, (e. g., nitrogen) as may also have entered into their 

 composition. All decay is simply a form of fermentation, that is 

 respiration, by Bacteria, or, in some cases, by simple Molds. 



Another phase of the same phenomenon is involved in those 

 deadly diseases which are caused by Bacteria, Asiatic Cholera, 

 Tuberculosis, Diphtheria, Typhoid, Lockjaw, and a number of 

 others. It is a popular belief that Bacteria produce their effect 

 in disease by destroying the tissues, or, as a plain-spoken student 

 of mine once expressed it, they "chew you all up inside." That 



