Notes. 
386 
ON THE RELATION BETWEEN THE FORMATION 
OF TUBERCLES ON THE ROOTS OF LEG-UMINOSAE 
AND THE PRESENCE OF NITROGEN IN THE SOIL.— 
At the meeting of the British Association in Manchester, 1887, 
I read a short paper on this subject describing certain water-culture 
experiments with the Bean (Vicia Faba), which tended to show 
that the development of tubercles is directly related to the absence 
of assimilable nitrogen in the surrounding medium. I now give 
a brief account of some further experiments with the same plant 
which confirm this conclusion. In both these experiments the Beans 
were grown in boxes containing well-washed sand. 
Experiment I. This experiment was conducted in a greenhouse ; 
one end of each box was exposed to direct sunlight, the other being 
always in the shade. 
1888. Feb. 24. 130 seeds were selected; 65 of these were soaked in 
1 litre of 1 p. cent. KN 0 3 solution and 65 in water. 
„ 26. The 65 seeds soaked in KN 0 3 solution were sown in 
sand in one box (A), and the remainder of the solution 
was poured over the sand in the box. The 65 seeds 
soaked in water were sown in sand in another box (B). 
,, 28. Sprinkled 10 grams KN 0 3 over sand in box A. 
Mar. 
55 
5. First appearance of plants above ground. 
7. Added to A : added to B : — 
10 grams MgS 0 4 10 grams MgS 0 4 
„ ,, Ca 3 2P0 4 ., ,, Ca 3 2P0 4 
„ „ KNCL „ „ KC 1 . 
„ 23. Box A: added 10 grams KN 0 3 ; 
Box B : one plant pulled up and examined, no sign 
of tubercle on its roots. 
Apr. 14. Examined from box A : 5 plants; no sign of tubercle, 
added 10 grams KN 0 3 . 
>> B. 4 jj 
tubercle on three. 
„ 21. 
A : 5 „ 
no tubercle. 
5 5 
B : 5 „ 
tubercle on all. 
„ 3 °* 
„ A: 6 ., 
one plant with tubercle. 
B : 6 „ 
tubercle on all. 
May 5. 
„ A: 10 „ 
one plant with tubercle. 
