162 
Barns, Regeneration and its relation to traumatropism. 
C. In tliis set of experiments tlie roots after wounding were 
allowed to grow but tlie traumatropic curve was prevented. For 
this pnrpose glass tubes of small bore were nsed. After being 
wonnded 1 mm from tlie tip witli tlie liot glass rod, tlie roots 
were inserted into tlie glass tubes and tlie preparations were kept 
in a dampcliamber or in water. The tubes varied in lengtli from 
3 to 8 cm. The roots then must grow from 1 to 6 cm betöre 
they can produce tlie traumatropic curve. 
1. Eiglit roots were wounded and placed in tubes 8 cm long. 
May 20 th. 1902. 
No. 1. Game out and gave curve of 45 degrees. 
2 60 
55 55 57 75 57 7 ? 77 77 
77 77 . 77 77 g^W Straight. 
The other tive died in the tubes. 
2. Roots wounded as in the previous experiment, May 16th. 
at 10 A. M. 
Distance 
root must 
Amount of growtli 
Angle of curvatnre 
grow in tube. 
]\lav 17 th. at 8 P. M. 
May 
19 th. 
No. 
1. 
6 
cm 
4 cm 
60 degrees. 
77 
2. 
4 
77 
3 _ „ 
20 
* * 
75 
3. 
5 
77 
* 4.5 ,, 
45 
75 
4. 
5 
77 
4 9 
„ 
10 
7 ? 
57 
5. 
5 
77 
4.5 „ 
90 
77 
77 
6. 
3 
77 
out 
60 
77 
7. 
4 
77 
77 
60 
77 
3. 
These roots were allowed to grow either in water 
or in a danip chamber and in a short time all turned 
down in answer to gravity. 
A number or experiments were set up to deter- 
mine tlie lengtli of time a root can hold tlie influence 
of the geotropic Stimulus. This was done for the 
sake of comparison. Uninjured plants whose roots 
were from 2 to 3 cm in lengtli were placed in plaster- 
casts and tlien left in damp sawdust in a horizontal 
position from 30 minutes to 15 hours. At tlie end 
of this time some were reversed so that gravity 
worked in the opposite direction from what it did 
at first, others were placed in a vertical position, and 
still others were taken from tlie horizontal position 
and placed on the klinostat. They were left under 
tliese condit.ions from one to seven hours wlien they 
were removed from the casts and all placed on the 
klinostat in a damp chamber. The results are shown 
in the following table. 
All of these roots curved immediately on leaving 
the tubes except number 6 wliicli grew straight 2 mm 
and then developed a traumatropic curve. I am not 
adle to account for this fact. 
