Soil Organisms concerned in Nitrogen Cycle. 



529 



Table XIV. 



Flask. 



Contents. 



In 24 Lours, 10 c.c. 

 required 



In 48 hours, 10 c.c. 

 required 



10 

 11 

 12 



13 



14 



15 

 16 



c.c. acid 



100 c.c. ammonifying culture 22 '5 



„ " , 22-0 



„ 22-4 



22-5 



100 c.c. ammonifying culture + 

 alcoholic extract of 1 grm. 

 bacterised peat 



100 c.c. ammonif ying culture + 

 phosphotungstic fraction of 

 1 grm. bacterised peat 



100 c.c. 

 silver 



ammonifying 

 fraction of 



bacterised peat 



21 -8 



mgrm. !VH 3 . 

 38-25 



37 -40 

 38-18 



38 -25 



37 06 



22 -4 



38 18 



22 



•4 



38 -18 f 



22 -5 



38 -25 



22 



"5 



38 -25 | 



22 -0 



37 -40 



22 



•4 



38 -18 J 



21-8 



37 -06 



22 



•5 



38 -25~1 



c.c. acid 



22 -2 



23 -0 

 22 -5 

 22 -5 



22 -3 



■ mgrm. 2*H 3 . 



37 -74] 



38 "25 J 

 37 



■38 13 





22 -0 



37 -40 



22 



■8 



38-76 I" 38 33 





22 -0 



37 -40 



22 



•3 



37 -91 | 





22 3 



37 "91 



22 



•6 



38 -42 J 



culture + 



21 -8 



37 -06 



22 



•4 



38 18^ 



1 grm. 















22 -2 



37-74 



22 



•4 



38 -18 \ 37 ' 83 





21 -9 



37 23 



21 



•6 



36-72 | 





22 



37 -40 



22 



•5 



38 -25 J 



These experiments were repeated over and over again, examinations being- 

 made of the ammonia produced at the end of periods varying from 6 to 

 96 hours, but always with similar results. No effect whatever was observed 

 upon the rate of ammonia production, and, in view of the increased activities 

 of the nitrogen-fixing and nitrifying organisms following upon the addition 

 of the auximones to their culture solutions, these results were at first 

 surprising. However, it should be pointed out that these substances are 

 produced in the peat during its " bacterisation," which results in the forma- 

 tion of a certain quantity of ammonium humate, and that they are therefore, 

 at least partially, the products of a bacterial action somewhat similar in 

 nature to the ammonifying process itself. It is scarcely to be expected 

 therefore that the activities of the organisms would be affected by substances 

 bearing a close relation to their own products, unless, as in the case of the 

 nitrifying bacteria, these products had accumulated in such amounts as to 

 bring about an inhibitory effect. 



The auximone fractions, however, as has been shown above, have the effect 

 of increasing the rate of nitrification in soil and in culture solution, yet they 

 have no effect upon the rate of ammonification. These results appear to be 



vol. Lxxxrx. — b. 2 y 



