FIXATION OF FEEE NITROGEN. 



149 



The white clover was sown in July 1890. Pot 1 was with 

 sand and ash without microbe-seeding; pots 2 and 3 the 

 same with microbe-seeding ; pot 4 with garden-soil ; and pot 

 5 with sand and ash, sterilised, but with calcium-nitrate 

 added. Pot 1 gave no cutting, but pots 2, 3, 4, and 5, each 

 gave many cuttings ; and the plants were not taken up until 

 December 1892. On the roots of the plants in pot 1 with- 

 out microbe-seeding there were no nodules, and there was 



SAND K VSH, 

 M I. Kl I.J XI I) 



s \ND x \sii 



SANDY-SOIL 



Pot 1. Pot 2. Pot 3. 



Fig. 5.— YELLOW LUPINS. 



Pot 4. 



extremely limited growth ; on those in pots 2 and 3 with 

 microbe-seeding there were many nodules, and in each case 

 the produce contained several hundred times as much nitro- 

 gen as that in pot 1. There was obviously, therefore, great Great gain 

 gain. The plants grown by the nitrate also contained several ™ nitrogen. 

 hundred times as much nitrogen as those in pot 1, but there 

 were no nodules on the roots. 



The red clover was sown in July 1889, yielded many 



