212 BOTANY 



into an alcoholic liquid, containing small amounts of glycerine, 

 succinic acid, and ester-like compounds in which the yeast itself can no 

 longer thrive. The nourishing material of the litre of grape-juice could 

 have supported a vastly larger quantity of yeast had the fermentation 

 not set in. In the same manner, when Mucor-fungi attack an apple, 

 they not only take the small amount of organic matter necessary for 

 their sustenance, but at the same time convert the whole apple into 

 a soft decaying mass. In addition to this peculiar nutritive activity, 

 intramolecular respiration (p. 219) is also active in the promotion of 

 fermentation and putrefaction. A considerable degree of heat is also 

 evolved in the course of these processes. The utilisation of this 

 heat in making hot-beds is a familiar practice. The heat produced by 

 damp fermenting hay or raw cotton may often become so great that 

 spontaneous combustion ensues. In germinating Barley an increase 

 in temperature of from 40 to 70 or more degrees has been observed. 

 The development of so much heat in this case is not due solely to the 

 respiration of the barley seeds, but, according to Oohn, to the decom- 

 posing activity of a fungus (Aspergillus fumigatus). The spontaneous 

 combustion of raw cotton is, on the other hand, caused by a Micro- 

 coccus. Coagulated albumen and thick gelatine are rendered fluid 

 by many Fungi and Bacteria, while the escaping gases (carbonic acid, 

 sulphuretted hydrogen, ammonium sulphide, ammonia, etc.) show 

 how deep-seated is the decomposition. It is by similar processes of 

 decomposition that dead organic matter becomes thoroughly dis- 

 organised and rendered harmless. To the decomposing action of 

 Fungi and Bacteria is due the severity of many diseases which they 

 produce in living organisms (potato disease, wheat smut, cholera, 

 typhus, diphtheria, anthrax, etc.). By the possession or formation 

 of substances (alexine, antitoxine), which react as specific poisons 

 upon the infecting Bacteria, plants, and particularly animals, in turn 

 protect themselves against the attacks of such micro-organisms. It is 

 due to a knowledge of this fact that the science of Therapeutics has 

 been enabled to cope more and more successfully with infectious 

 diseases. 



Fungi and Bacteria, in addition to the power, dangerous to them- 

 selves, of disorganising their own nutrient substratum by fermentation 

 and putrefaction, also possess the capability of making an unsuitable 

 substratum suitable for their sustenance. By means of inverting 

 ferments they can convert an unsuitable cane-sugar into an available 

 grape-sugar, and by their diastatic ferments they are able to form 

 starch from glucose and maltose. 



As is evident from their thriving upon such various substrata, 

 Fungi have the power of producing from the most different carbon 

 compounds (and also from nitrogenous mineral compounds such as 

 ammonium tartrate, or even ammonium carbonate) protoplasm, cell 

 wall, nuclein, fat, glycogen, etc. It is also an astonishing fact that, 



