164 
Bur ns, Regeneration and its relation to traumatropism. 
prolonged as was apparently shown by tbe second set of ex- 
periments. 
The other question finds its solution, as I believe, ir» the 
third set of experiments. Is the influence of the Stimulus con- 
ducted to the elongating zone and there held until the root is 
free to respond to it? This experiment with the glass tubes is 
free from the objections cited before against the method of 
cutting away the wounded tissue. Roots wounded and grown 
in tubes grew as high as 6 cm and responded to the Stimulus 
over two days after they were wounded. If now the influence 
of the Stimulus was conducted to the elongating area immedia- 
tely and there held it must have returned down the root as it 
elongated. This seems highly improbable although we have some 
evidence that the traumatropic Stimulus may be conducted toward 
the tip as well as in the opposite direction. 
The work seems to justify the following conclusions: 
1. That the influence of the Stimulus is not conducted to 
the elongating zone and there held from one to ' 
eight days. 
2. That the latent period is not prolonged by mechanical 
means. 
3. That the wounded tissue forms a constant irritant. 
4. That this irritant is remöved when regeneration is 
complete. 
University of Michigan, January 4, 1904. 
Literature. 
1) Prantl, Untersuchungen über die Regeneration des Vegetationspunktes 
an Angiospermenwurzeln. (Arbeiten des Bot. Inst, in Würz¬ 
burg. Bd. 1. p. 546. (Older literature is cited liere. 
Lopriore, Über die Regeneration gespaltener Wurzeln. (Nova Acta 
Leop. Carol. 66. No. 5.) His other papers are cited here. 
2) S pal ding, On the traumatropic curvature of roots. (Annals of Botanv. 
Vol. 8. 1894.) 
3) „ 1. c. p. 448. 
4) „ 1. c. p. 438. 
5) „ 1. c. p. 450. 
Explanation of flgures. 
Pisum sativum six days after branding. The wounded tissue lias 
been regenerated and the root is turning down. 
Pisum sativum. Radical six liours after release from plaster-cast in 
whicli it had been confined 72 honrs after previons branding. 
Pisum sativum. This radical, after being wounded, grew 4 cm in the 
tube and developed a traumatropic curve on leaving it. 
Pisum sativum. Small part of a longitudinal section of a root-tip 
wliich was killed 48 houi’S after wonnding. The process of rege¬ 
neration is not complete. 
No. 1. 
No. 2. 
No. 3. 
No. 4. 
