30 



Mr. A. D. Hall and Dr. N. H. J. Miller. [Mar. 30, 



contents were sterilised ; when cool they were seeded with - 2 gramme of 

 partly dried surface soil recently drawn from Plot 2 on Broadbalk Field, and 

 the flasks placed in a dark cupboard at the ordinary laboratory temperature. 

 The results are summarised in Table XV, and serve to show that the soil 



XV. — Bacterial Decomposition of Calcium Oxalate. 



Refer- 

 ence 

 No. 



1 



.Added to nutrient 

 solution at starting. 



Duration, 

 days. 



| 



CaCo.3 found 

 from 

 1 gramme 

 CaC 2 4 . 



Reaction 

 at end. 



State of nitrogen compounds 

 at end. 



46 



No soil added 



79 













50 



No calcium oxalate ... 



79 



"015 



Neutral 





61 





176 



trace 



j) 



StroDg nitrite, slight nitrate. 













Ammonia. 



44 



Neutral 



79 



-263 



)> 



Nitrate, no nitrite nor am- 













monia. 



62 





176 



316 



s> 



Nitrate, sliglit nitrite, no 













ammonia. 



43 



Slightly alkaline 



73 



0-428 



s> 



Strong nitrite, nitrate. 



64 





176 



274 



!J 



Slight nitrite, strong nitrate, 













no ammonia. 



42 



+ P 2 glucose, neutral 



79 



0-105 



5J 



No nitrite nor nitrate. 



58 



+ 0-2 „ 



78 



052 



>> 



No nitrite nor nitrate. Am- 













monia. Glucose gone. 



52 



+ 0'2 „ alkaline 



73 



0-184 



)) 



Little nitrite, no nitrate, no 













glucose nor ammonia. 



48 



+ 0"2 peptone 



80 



-183 



>) 



Nitrite, strong nitrate, no am- 













monia nor organic matter. 



59 



+ 0-2 , 



84 



0-184 



)) 



Strong nitrite and nitrate, 













some ammonia, no pep- 













tone. 



47 



+ 0"2 calcium humate 



82 



-182 



It 



Nitrite and nitrate, no am- 









1 





monia. 



60 



+ 02 „ 



176 



195 



5) 



Slight nitrite, strong nitrate, 













no ammonia. 



63 



+ 0-2 „ 



176 



-144 



)> 



Slight nitrite, strong nitrate, 













no ammonia. 



contains one or more organisms which are very effective in converting 

 calcium oxalate into carbonate. The mechanism of the reaction is being 

 further studied ; in the present connection the experiments are sufficient to 

 show the existence of other agencies of a bacterial nature engaged in restoring 

 calcium carbonate to the soil. 



The destruction of nitrates by bacterial action, with the evolution of the 

 nitrogen as gas, the change commonly known as " denitrification," is always 

 attended by the production of a carbonate of the base with which the nitric 

 acid was combined, but as any calcium carbonate formed in this way would 

 only replace the calcium carbonate consumed in the previous nitrification 

 there would be neither gain nor loss to the soil. As also denitrification is 

 most likely to take place in the lower subsoil where the oxygen of the soil 



