Burns, Regeneration and its relation to traumatropism. 101 



Experiments. 



A. Seedlings were allowecl to remaiii in sawdiist iintil the 

 root was 2 or 3 cm long. They were then wounded by branding 

 witli a liot glass rod as described, and placed in a damp Chamber 

 in a vertical position. The temperature was about 22" C. 



Seven peas were branded 1 mm l'rom the tip. 

 No. 1. Described a circle and died. 

 ., 2. Curved at an angle of 100 degrees. 

 '•^ QD 



„ 4 90 



ö 90 



"I 77 '? 77 77 77 *-'^-' -7 



„ 7. ,; „ , .. .. 00 .. 



., 8. Control. Grew straight. 

 The roots continnod to grow at aboiit the angles indicated for 

 some time. Giadually they tnrned in response to gravity some 

 of them at right angles while others never reached the vertical 

 position. The lengtli of time dm:ing 

 which the root did not respond to gravity 

 varied with different roots according to 

 the severity of the wound. 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 turned down al- 

 inost at right angles. The root grew well ^' 



(Uu'ing all of this time. (Fig. 1). 



One important Observation was made 

 on this set of seedhngs which led to the So- 

 lution of the problem. It was noticed that 

 about the time that the root-tips tiu-n ^^S- 1- 



down the wounded tissue either had disappeared or remained as 

 a little brown diso on the root. This was easiliy removed with 

 a needle. As this subject receives careful conside- 

 ration in a foUowing paragraph 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 l)y 3 cm, adding a very little plaster 

 and finally a second glass plate the same size as the 

 first. After the preparations had hardened a little they 

 were tied firmly 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 tijis and placed in 

 a damp Chamber or on the klinostat. The results were 

 the same as those recorded by Spalding. The roots Fig. 2. 

 developed a traumatropic curve. (Fig. 2.) Apparently the latent 

 period has been prolonged by this mechanical meaus. 



Beihefte Bot. Contralbl. Bd. XVtU. Abt. I. Heft 1. 11 



