HUMUS 79 



formed either with Tyrosine or Asparagine which 

 contain no carbohydrates. 



It is to some extent on the basis of the above 

 experiments that Professor Bottomley has estab- 

 lished his method for introducing bacteria into the 

 soil. In his paper in the Biochemical Journal he 

 drew the following conclusions, which in view of their 

 important bearing on the subject of this book I am 

 quoting textually: 



' The general result of the investigation so far," 

 he writes, " has been to indicate that carbohydrates 

 generally and certain sugars in particular pass 

 through a regular series of changes when submitted 

 to the reactions described. It was also found that 

 air-dried sphagnum moss is readily acted on by 

 acids, with the formation of a brown, peat-like mass 

 from which Humic acid can be extracted. 



" One hundred grammes of air -dried sphagnum 

 moss, when boiled for twenty-four hours with 5 per 

 cent, solutions of Hydrochloric, Oxalic, and Lactic 

 acids respectively, yielded the following results : 



Humic Acid. 

 Hydrochloric Acid . . . . 11*7 grammes. 



Oxalic Acid . . . . . . 2-3 ,, 



Lactic Acid .. .. .. 1*8 ,, 



" The humic substances comprising the Humic 

 acid and Humin groups probably pass through a 

 series of changes characterized by a progressive 

 increase of their Carbon content. In ordinary 

 cultivated soils these changes cannot be traced, 

 owing to the constant addition of fresh organic 

 matter and cultural operations, but in peat beds, 



