102 



Sir J. B. Lawes and Prof. J. H. Gilbert. [Jan. 9, 



and seed together), taken as 1. It is seen that, even in pot 1, with 

 the impure and not sterilised sand, but without soil-extract, there 

 was, so reckoned, more than three times as much nitrogen in the 

 products as in the soil and seed ; in pot 2, with soil-extract, there was 

 about five times as much ; and in pot 3, also with soil-extract, there 

 was more than four times as much. In the case of pot 4, how- 

 ever, with garden soil, owing to the large amount of initial nitrogen 

 in the soil, the gain, so reckoned, appears but small. 



It is in the last column of the table, in which, disregarding the nitro- 

 gen in the soils, which remained so nearly constant throughout, and 

 reckoning the relation of the nitrogen in the total products of growth 

 to that in the seed taken as 1, that the large amount of fixation is 

 brought clearly to view. So reckoned, the nitrogen in the substance 

 grown was — in pot 1, 9£ fold ; in pot 2, nearly 18 fold ; in pot 3, 

 nearly 15 fold ; and in pot 4, nearly 22 fold, that supplied in the seed. 



The Vegetation Experiments in 1889. 



In this second season a more extensive series was arranged. The 

 plants selected were — peas, red clover, vetches, blue lupins, yellow 

 lupins, and lucerne. For the lupins and lucerne, specially made pots 

 of glazed earthenware, about 6 inches in diameter, and 15 inches deep 

 inside, that is about twice as deep as the pots used in 1888, and as 

 used again for the peas, red clover, and vetches, were employed. 

 These pots had holes at the bottom for drainage, and slits at the 

 side, near the bottom, for aeration. All the pots stood in specially 

 made saucers or pans of the same material. A quantity of broken, 

 washed, and this time ignited flint, was put into the bottom 

 of each pot. The sand used was a rather coarse white quartz sand, 

 from which the coarser and the finer portions were removed by sifting, 

 and more of the finer by washing and decantation, first with well, and 

 afterwards with distilled water. In defect of means for igniting so 

 large a quantity of material (about 300 lbs.) without running the 

 risk of gaining more impurity than was expelled, the portion 

 retained for use was kept, in successive lots, in a large water-bath, 

 at nearly 100° C, for several days, and then preserved in well-closed 

 bottles. The results will show that the sand so prepared was suffi- 

 ciently, if not absolutely, sterilised. 



In each case the sand was mixed with 0*1 per cent, of the plant-ash, 

 and 0'1 per cent, of calcium carbonate. 



There were four pots of each description of plant. Of the peas, 

 clover, vetches, and lucerne, No. 1 was with the prepared quartz sand 

 without soil-extract ; No. 2 with the quartz sand and garden soil 

 extract added ; No. 3 was duplicate of No. 2 ; and No. 4 was with 

 the garden soil itself. Of the blue and yellow lupins, No. 1 was with 



