28 TRANSACTIONS AND PROCEEDINGS OF THE [Sess, LXI. 



acted on by other organisms, the so-called nitrifying 

 bacteria ; the nitrous organism converting the ammonia 

 into nitrous acid, this nitrous acid by the agency of the 

 nitric organism passing into nitric acid, from whose union 

 with a base come the nitrates so important as the form in 

 which plants obtain that nitrogen, without which their 

 growth and development is impossible. There is then a 

 sort of circle of changes by which the nitrates taken up 

 by the plant once more find themselves as nitrates in 

 the soil, on the completion of the^circuit in which bacteria 

 play so important a part. 



Nitrates from soil 

 into plant -^^^ 



Nitrous acid to nitric Changed into albu- 



acid by nitric men in the plant, 



organism. which 



V 



Ammonia to nitrous Eaten by a vegetarian 



acid by nitrous animal takes its 



organism. share in the forma- 



Vtion of protoplasm 

 y 



iJecoiaposed by The vegetarian 



bacteria of putre- preyed on by a 



faction, x^hence carnivorous form 

 ammonia. 



" Death," as Liebig says, " the source of a new generation " ; 

 or, as Klein quotes, " from earth to earth." 



Morphology of the Nitrifying Organisms. — Globular to 

 begin with, but later, oval and somewhat elongated. The 

 nitrous organism is larger than the nitric, and measures 

 :>3^oo inch. 



(Jonditio7is which favoivr Nitrification vjith Annotations. — 

 1. The presence of the organisms. — These organisms vary 

 in number greatly in different soils. The more highly 

 cultivated .soils will contain them in greatest quantity. 

 Where they are few in number what has been termed 

 " microbe-seeding " may be wisely practised, i.e. soils 

 which, owing to their deficiency in these organisms, can be 

 looked on as .so far sterilised, could have added to them soil 

 which from the conditions was known to be rich in nitrify- 

 in j; germs. If the new environment wei"e favourable the 



