524 Miss F. A. Mockeridge. Effects of Auximones on 



by Bottomley,* and no nitrate was formed in the medium. It was only after 

 long-continued sub-culturing that a nitrifying culture was obtained free from 

 these organisms, and the experiments recorded were carried out with this 

 comparatively pure culture. 



A preliminary experiment showed that the water extract of bacterised 

 peat is directly nitrifiable, hence the effect of this extract upon the rate of 

 nitrification in normal nitrifying solution cannot be tested. An experiment 

 was therefore made to determine whether the auximone fractions had any 

 effect upon the rate of nitrification in ammonium sulphate solution. Portions 

 of 100 c.c. of Winogradsky's medium, described above, were put into each of 

 24 flasks, divided into four series of six each, with the additions < shown in 

 the Table below. When all had been inoculated, and two of each series 

 sterilised for controls, the whole set was incubated at 26° C. for seven days. 

 The nitrate content of 25 c.c. of each was then estimated as before, with the 

 following results : — 



Table XL 



Flask. 



Contents. 



Nitric nitrogen 

 in 25 c.c. 



Nitric nitrogen 

 in whole. 



1 



2 

 3 

 4 

 5 

 6 



7 

 8 

 9 



10 

 11 

 12 



13 

 14 

 15 



16 

 17 

 18 



19 

 20 

 21 



22 

 23 

 24 



Control 



100 c.c. Winogradsky's medium 



>> a >j 



j) j) >j 



j> >> ?i 



Control 



100 c.c. Winogradsky's medium + alcoholic extract 

 of 1 grm. bacterised peat 



>j >» >) i) 



J? j> >) jj 



)> j) j) )) 



Control 



jj •■• 



100 c.c. Winogradsky's medium + phosphotungstic 

 fraction of 1 grm. bacterised peat 



)> >) )> >> 



j) >> j> j» 



jj ?) )> n 



Control 



)) ; 



100 c.c. Winogradsky's medium + silver fraction of 

 1 grm. bacterised peat 



mgrm. 





o-oi 







0-009 







0-18 







0-21 







0-20 







0-18 







o-oi 







0-01 







0-31 



1 



0-30 



1 



0-27 



1 



0-28 



1 



0-009 







0-009 







0-27 



1 



0-31 



1 



0-27 



1 



0-29 



1 



o-oi 







o-oi 







-34 



1 



0-36 



1 



0-39 



1 



0-35 



1 



•038 



.0-77 



24 



0361 

 036 J 

 08 i 



•16 



•036 



J»l -14 



36 1 



I-1-44 



* Bottomley, W. B., ' Roy. Soc. Proc.,' B, vol. 89, pp. 102-108 (1915). 



