GENERAL FUNCTIONS OF MICROBES 7 



more highly organised, and by the nitrifying and denitrifying 

 bacteria. 



Pectose is a hydrocarbon associated with cellulose in the 

 membranes and interstices of plant cells ; the rust which 

 attacks hemp and linen is a fermentation of the pectose, 

 transforming it into pectic acid, then to sugar, by the B. 

 amylobader and by the Granulobacter of Fribes and Winograd- 

 sky. In the manure heap, aerobic fermentation proceeds at 

 the surface and raises the temperature up to nearly 80° C. In 

 the depths of the heap the temperature is low, and there the 

 anaerobic ferments attack the cellulose. The bubbles which 

 rise and burst on the surfaces of ponds are signs of the 

 anaerobic fermentation which is decomposing organic debris at 

 the bottom. Manure kept in a latticed box with free access of 

 air heats up without there being destruction of the cellulose ; 

 loss of nitrogen takes place. Manure heaped in a closed box 

 or kept corked in a large carboy, liberates methane from the 

 decomposition of the cellulose. It is possible to collect the 

 gas and by means of an exit tube to make it furnish a light. 



It was a natural step to attribute to the ferments of 

 cellulose the formation of peat, lignite and coal. Microbes 

 certainly are at work in the^ decomposition of vegetable matter 

 in the peat-bogs, and coal is supposed to be the product of more 

 complete fermentations, two varieties at least of bacteria being 

 in activity in succession ; the first dissolves the central 

 membranes of the cell walls, the others attacking the cellulose, 

 more or less pure, which constitutes the thick parts of the wall. 

 " The bacterial activity," says the most convinced defender of 

 this theory, "produced a de-hydrogenation and de-oxidation, 

 the final result being the production of carbon. We do not 

 know if the final limit of this process has ever been reached, 

 but figures show that the more geologically ancient the fuel, the 

 more carbon it contains " (Bernard Renault). Fuel of less 

 age, lignite, and peat, for example, contains besides bacteria, 

 amcebse and infusoria. In the lignites, the cannel coals, and the 

 boghead coals, we find fungi and algae, which do not occur in 

 coal proper. Bacteria alone exist in all the fuels ; they are 



