Bums, Regeneration and. its relation to tranmatropism. 
1 (53 
No. of 
Time in hori¬ 
Time in ver- 
Time in reversed 
Time on hlino- 
Results when re¬ 
seeds. 
zontal position 
tical position 
horizontal position. 
stat in casts. 
moved from casts 
in casts. 
in casts. 
and revolved on 
klinostat. 
20 
lOlirs. 
1 hr. 
Kesponded to 
first stimulns. 
15 
15hrs. 
1 hr. 
ditto. 
20 
15hrs. 
2 hrs. 
Responded to the 
second Stimulus. 
37 
51irs. 
7 hrs. 
Grew straiglit. 
10 
1 hrs. 
6hrs. 
ditto. 
10 
10 min. 
1 hr. 
9 grew straight 
1 developed the 
curve. 
A study of tliis table shows that roots are able to bold tlie 
influence of a geotropic Stimulus for a very short time only. It 
would be interesting to determine the exact lengtli of time but 
from the standpoint of this paper it is not essential. 
Anatomical studies. 
In the foregoing experiments it has beeil noted that the roots 
turned down in answer to gravity after a certain lengtli of time. 
Roots were killed and sectioned longitudinally to study their 
structure at the time when this change took place. Those 
roots were selected on wliich the brown mass of dead tissue still 
remained. This usually dropped off during the process of im- 
bedding but by using a large part .of the root it was not hard 
to get sections through that part of the root which had been 
wounded. A study of these sections showed no trace of the 
wound. The process of regeneration was completed. 
A series of sections was now made from roots which had 
been wounded and which still showed a 
marked traumatropic curve. Figure 4 shows 
part of the longitudinal section of a root 
which was killed 48 hours after wounding. 
At the time it was killed it was growing 
at an angle of 90 degrees. The figure shows 
that the wound has not been regenerated 
but that process is still going on. 
Discussion and coiiclusions. 
A review of the facts obtained by the experimental work 
cited in the preceding pages show that tlie two phenomena. re¬ 
generation and traumatropism, are very closely connected in tlie 
case of the root-tips examined. 
The first set of experiments, taken in connection with the 
anatomical work, show clearly tliat as long as wounded tissue is 
found, the root will form a traumatropic curve. Or in other 
words, when the process of regeneration is complete the Stimulus 
causing the curve is removed. Tliis seems to show then, that 
liiere is a constant irritant and that the latent period is not 
11* 
