1890.] On the Question of the Fixation of Free Nitrogen. 97 



In pot 8, "with the garden soil, there were three plants, two of them 

 small ones from more recent sowings than the other, and with mnch 

 less root development ; bnt there were three or f onr nodules or swel- 

 lings on the root-fibres of each plant. The largest and oldest plant 

 showed a very great development of root, extending throughout the 

 soil, round the sides, and along the bottom of the pot. On the main 

 root, which was thick and strong down to about 5 inches, there were 

 two large swellings or nodules about 3 inches from the surface, each 

 of which, unlike the bunches of nodules on the pea roots, appeared 

 externally to be single and solid, but indented. There were, besides, 

 nineteen small swellings on the root-fibres, of the same colour as the 

 root itself, and whether these were nodules or not was not very 

 obvious. 



In pot 9, in the yellow sand without soil-extract, there were two 

 plants of yellow lupins. With less above-ground growth, there was 

 also considerably less root development, than under the same soil con- 

 ditions with the blue lupins (pot 5). As in the case of the blue 

 lupins, there were, however, no nodules. 



In pot 10, with lupin-soil-extract seeding, there were two small 

 plants, also with small root-development, but throwing out much fine 

 fibre near the surface, and then slender branches to the bottom of the 

 pot. There were here, again, no nodules. 



In pot 11, with the lupin sand, there were two plants, one very 

 much larger than the other. There was a swelling on the thick main 

 root of the smaller plant, but there were no nodules on the rootlets. 

 The larger and older plant developed a dense mass of both fleshy and 

 fine fibrous root. The main root, about 1 inch from the surface, 

 was encased by a large swelling. The roots extended from the top 

 to the bottom of the soil. No nodules were observed on the rootlets, 

 but there was an abundance of root-hairs. 



In pot 12, with garden soil, there were two plants. The stout, 

 woody, main root, extended deeper than in the other pots ; and there 

 were many branches, extending round the sides and along the bottom 

 of the pot. The larger plant had two swellings on the main root, 

 about 1^ inch from the surface, each of the size of a field bean ; also 

 three small nodules on the root-fibres. The smaller plant had one 

 indication of such a swelling on the main root, and twelve nodules on 

 the root-fibres, three the size of a pea, three half as large, and six 

 very small. The larger were 1 or 2 inches from the surface, the 

 others lower, one 6 inches down. There was more fine fibre, but 

 very much less development of root-hairs than in pot 11. 



Thus, in the case of both blue and yellow lupins, there were no 

 nodules without soil-extract, and only one with the lupin soil-extract 

 seeding. In the lupin soil itself there was some indication, but in 

 the garden soil there was, with both descriptions of lupin, a much 



