notice the offices of some other bacteria in the 

 soil. 



Organic matter containing nitrogen, such as 

 manure, is converted by fermentation into ammo- 

 niacal compounds. By one kind of micro-organ- 

 isms in the soil these compounds are oxidized into 

 nitrites, and by another kind the nitrites are raised 

 to nitrates, 1 ready for absorption by the roots of 

 plants. Both organisms are found in all good soils; 

 in the future farmers may sow them in bad soils, 

 not forgetting to sow with them some phosphates, 

 sulphates, etc., as foods for the micro-organisms 

 themselves. 



Here, as very frequently elsewhere, man is de- 

 pendent upon bacteria for some of the good things 

 in life. In these days of antisepsis, when the tend- 

 ency is to sterilize everything, especially our foods, 

 it may soften our animosity towards the disease- 

 producing micro-organisms to reflect that there are 

 many of their kin which are friendly to us : the 

 delicate flavors given to butter and to cheese are the 

 results of their action ; even the process of digestion 

 is probaby dependent in a manner upon them. 



But what has electricity to do with the action 



1 When we consider how scarce and costly nitrates are, we 

 can rightly value the work of these two kinds of bacteria. 

 They make the nitre beds of Chili and India by converting 

 the organic matter deposited there by fish-feeding sea-birds 

 into nitrates of soda and potash. The absence of rain in these 

 localities causes the nitrates to effloresce upon the dry soil, 

 from which they are easily collected ; in other places they are 

 washed away on account of their great solubility in water. 



