274 Hooker.—Hydrotropism in Roots of Lupinus alhus. 
Experiment I. 
No. of 
Distance from 
Average 
Growth 
tray. 
filter-paper. 
groivth. 
per hour. 
1 
5 cm. 
16*8 mm. 
0*93 mm. 
II 
10 cm. 
ii*o mm. 
o*6i mm. 
III 
15 cm. 
8*4 mm. 
0*46 mm. 
IV 
20 cm. 
7*2 mm. 
0*40 mm. 
This experiment covered eighteen hours. One hygrometer 3 cm. 
distance from the filter-paper measured 97 per cent., and another 28 cm. 
distant measured 90 per cent, relative moisture. Three roots in I, two 
each in II and III, and one in IV bent towards the filter-paper. The 
reaction was observed in I and II at the end of seven hours, and in III and 
IV half an hour later. 
Experiment II. 
No. of 
Distance from 
Average 
Growth 
tray. 
filter-paper. 
growth. 
per hour. 
I 
5 cm. 
19*4 mm. 
o*97 mm. 
II 
10 cm. 
17*2 mm. 
o*86 mm. 
III 
15 cm. 
11-6 mm. 
0*58 mm. 
IV 
20 cm. 
6*2 mm. 
0*31 mm. 
The experiment lasted twenty hours. The hygrometers measured 
87 and 98 per cent, respectively. After six hours three in I began to bend, 
and an hour later four in II, and two each in III and IV, bent towards the 
filter-paper. The remaining roots grew straight. 
Experiment III. 
No. of 
Distance fro?n 
Average 
Growth 
tray. 
filter-paper. 
growth. 
per hour. 
I 
5 cm. 
18*2 mm. 
0*76 mm. 
II 
10 cm. 
1 i*o mm. 
0*46 mm. 
III 
15 cm. 
8*6 mm. 
0’25 mm. 
IV 
20 cm. 
6*o mm. 
0*25 mm. 
This experiment lasted twenty-four hours. The hygrometers measured 
88 and 96 per cent, respectively. After six and a half hours three roots in 
I and two in II and IV bent positively towards the source of moisture. 
Experiment IV. 
No of 
Distance from 
Average 
Growth 
tray. 
filter-paper. 
growth. 
per hotir. 
I 
5 cm. 
17*6 mm. 
o*8o mm. 
II 
10 cm. 
9*8 mm. 
o*45 mm. 
III 
15 cm. 
6*2 mm. 
0*29 mm. 
IV 
20 cm. 
3*6 mm. 
0'i6 mm. 
The experiment lasted twenty-two hours. A tray with sulphuric acid 
(90 per cent.) was placed in the end opposite the filter-paper. The hygro¬ 
meters measured 83 and 95 per cent, respectively. One root each in I, III, 
and IV bent positively after seven and a half hours. One root each in 
III and IV was curved negatively. 
