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



Table XIII. 



Flask. 



Contents. 



Acid 

 neutralised. 



NH 3 present. 



10 

 11 

 12 



13 



14 

 15 

 16 



Soil + 1 per cent, peptone 



Soil + 1 per cent, peptone + alcoholic extract of 

 1 grm. bacterised peat 



Soil + 1 per cent, peptone + phosphotungstic frac- 

 tion from 1 grm. bacterised peat 



Soil + 1 per cent, peptone + silver fraction from 

 1 grm. bacterised peat 



c.c. 



35 "0 



36 -1 



35 -5 



36 



mgrm. 

 59 '501 



to ll K 60 



61 -20 J 



35 -9 



61 03^| 



35 -7 



36 -0 

 36-2 



1 



60-69 i-61 -11 

 61 -20 | 

 61 -54 J 



36 -2 



61 -54^ 



36 -3 

 35 -8 

 35 -6 



61 -71 1 61 -16 

 60 -86 | 

 60 -52 ) 



36-1 



61 -37") 



35 -8 

 35 -6 

 35 -9 



60-86 i-60-94 



60 -52 | 



61 -03 J 



An identical series of experiments was carried out with each, of the soils 

 obtained from Kew, and these yielded similar results, all failing to show any 

 effect of the auximones, stimulating or otherwise, upon the ammonifying 

 power of the soils. In view of these results, an examination was made of 

 the influence of these substances upon the ammoniacal fermentation of urea. 



Tor this purpose, a mixed culture of ammonifying organisms was obtained 

 from rotting manure by inoculating the latter into a culture medium con- 

 sisting of Witte's peptone 1 grm., urea 10 grm., Lemco 5 grm., distilled water 

 100 c.c, the whole being neutralised with ammonium carbonate solution. 

 A drop of this mixed culture was then inoculated into a solution of urea 

 50 grm., mono-potassium phosphate 25 grm., sodium acetate 10 grm., distilled 

 water 1000 c.c, this solution also being just neutralised with ammonium 

 carbonate solution. The culture thus obtained was sub-cultured three 

 successive times into flasks of the same medium, three days' incubation 

 elapsing between each sub-culture. Sixteen flasks, each containing 100 c.c. 

 of the same medium, with the additions shown in the Table below, were then 

 inoculated each with 1 c.c of the culture of urea-splitting organisms thus 

 obtained. The whole set was incubated at 22° C, 10 c.c of each being 

 withdrawn after periods of 24 and 48 hours respectively, and titrated with 

 decinormal sulphuric acid, methyl orange being used as indicator. The 

 figures obtained were as follows : — 



