The Traumatropic Curvature of Roots 
BY 
VOLNEY M. SPALDING, 
Professor of Botany in the University of Michigan. 
With Plate XXII. 
Introductory. 
HE name Traumatropism has recently been given 1 to 
JL certain phenomena observed to follow the infliction of 
wounds upon the tip of growing roots, which apparently are 
to be classed with geotropism, hydrotropism, and other corre- 
sponding reactions to external stimuli. Inasmuch as the 
subject has hitherto received comparatively little attention, 
and the existing literature, though limited, is contradictory, it 
has seemed desirable to investigate it experimentally. Such 
a study, provided definite conclusions were reached, might be 
expected to throw light on the question as to whether the 
observed phenomena are to be classed as mechanical move- 
ments or as movements of irritability, a question upon which 
hitherto there has been total lack of agreement. In the 
course of the work certain other and unlooked-for results, of 
theoretical interest, have been brought out and will be spoken 
of in their proper place. 
The writer wishes to express his sincere thanks to Professor 
1 Pfeffer, Druck- und Arbeitsleistung durch wachsende Pflanzen, p. 374, Bd. xx. 
d. Abhl. d. math.-phys. Cl. d. Konigl. Sachs. Gesellschaft d. Wissenschaften. 
Leipzig, 1893. 
[Annals of Botany, Vol. VIII. No. XXXII. December, 1894.] 
