Eurns, Regeneration and its relation to traumatropism. 
161 
Experiments. 
A. Seedlings were allowed to remain in sawdust until the 
root was 2 or 3 cm long. They were tlien wonnded by branding 
with a liot glass rod as described, and placed in a damp cbamber 
in a vertical position. The temperature was about 22 0 C. 
Seven peas were brancled 1 mm from tlie tip. 
No. 1. Described a circle and died. 
57 
55 
55 
: 7 
2 . 
3. 
4. 
5. 
6. 
7. 
8 . 
Curved at an angle of 100 degrees. 
55 
55 
55 
55 
57 
55 
57 
75 
55 
55 
55 
55 55 55 55 # 55 
Control. Grr'ew straiglit. 
90 
90 
90 
80 
60 
Ei g. 1. 
Tlie roots continued to grow at about the angles indicated for 
some time. Gradually tliey tnrned in response to gravity some 
of tbem at right angles while otliers never reached the vertical 
position. The lengtli of time during 
which the root did not respond to gravity 
varied with different roots according to 
the severity of the worind. One root was 
especially noteworthy in that it grew at 
an angle of 80 degrees for six days. At 
the end of that time it tnrned down al¬ 
most at right angles. The root grew well 
during all of this time. (Fig. 1). 
One important observation was made 
on this set of seedlings which led to the So¬ 
lution of the problem. It was noticed that 
about the time that the root-tips turn 
down the wounded tissue either had disappeared or remained as 
a little brown disc on the root. This was easiliy removed with 
a needle. As this subject receives careful conside- 
ration in a following paragriph further mention at 
this place will be omitted. 
B. Seedlings whose roots were 2 or 3 cm long 
were wounded and placed in plaster-cats. This was 
best done by placing the root to be imbedded on a 
small glass plate 1 by 3 cm, adding a very little plaster 
and finally a second glass plate the sanie size as the 
first. After the preparations had liardened a little they 
were tied tirmly together. They were then placed in 
a vertical position in damp sawdust and allowed to 
remain from two to eight days. At the end of this 
time they were removed from the casts, which is very 
easily done without injury to the tips and placed in 
a damp chamber or on the ldinostat. The results were 
the same as those recorded by Spalding. The roots 
developed a traumatropic curve. (Fig. 2.) Apparently the latent 
period has been prolonged by this mechanical means. 
Beihefte Bot. Centralbl. Bd. XVHI. Abt. I*. Heft 1 . 11 
Ei g. 
