Regeneration and its relation to traumatropism. 
Bv 
George P* Burns. 
(Wim 4 images in tlie text.) 
It is a well known fact that plants are able to regengrate 
tissue at the root-tip, wlien such, tissue lias been destroyed, although 
tlie injury be so great that tlie entire tip be removed. 1 ) It is 
equally well known that when root-tips are wounded in any manner 
such as burning with a hot glass rod, cutting etc., within the 
sensitive zone, that they respond to the Stimulus, developing a 
traumatropic curve. 2 ) The intensity of this curve varies within 
large limits. In some cases the roots describes two circles while 
in others the angle of divergence from the perpendicular is very 
small. Those roots which develop the extreme curves were injured 
very severely and die almost without exception, the plant depending 
upon the development of lateral roots. 
The preceeding observations show that both regeneration and 
traumatropic curvature follow the sarne Stimulus. On this point 
Spalding says, 3 ) „the phenomena go hand in hand, and it seems 
impossible not to regard them as two different forms of Nach¬ 
wirkung resulting from tlie sarne cause“. 
The relation of regeneration to traumatropic curvature as 
seen in the root-tip has not been, as far as I know, a subject of 
special consideration. Spalding refers only to the biological 
signiflcance of tlie traumatropic curve when considered in Connec¬ 
tion with regeneration. He says, „In case of injury to the growing 
point of the root it is essential to tlie welfare of the plant that 
repair should take place as promptly and economically as possible. 
This is accomplished with remarkable rapidity by the process of 
regeneration. Meanwhile it is also important that while the work 
of repair is going on the root should avoid further contact with 
tlie source of injury. This is brought about by traumatropic 
curvature.“ 
In this sarne paper one division is devoted to a study of 
„Suspension of growth and its Relation to Traumatropic Curva¬ 
ture“. Roots of Lupinus albus, Yicia Faba, and Zea Mais were 
wounded and placed in plaster-casts. The casts were then placed 
in moist saw-dust in such a position that the roots were perpen- 
