VOLUME XXIII NUMBER 5 
BOTANICAL. CCAZETTIE 
MAY 1897 
THE CURVATURE OF ROOTS. 
D..T. MACDOUGAL. rm) 
(WITH PLATE XXVIII) 
I, INTRODUCTORY. 
In nearly all of the researches hitherto prosecuted upon 
“curvature” it has been assumed that movements of stems, 
petioles, leaves, petals, sepals and roots are accomplished by 
means of similar mechanisms, and the relation of the mechanical 
elements as well as the phylogenetic meaning of the movement 
have been ignored. Many writers have gone so far as to uphold 
the necessity of a common explanation for the mechanism of 
curvatures of unicellular, coenocytic, and multicellular organs, a 
Necessity by no means obvious. It has been customary also to 
‘regard the curvatures of tendrils and other organs highly special- 
2 ized i in structure as well as in function as identical in mechanism 
_ With stems from which they are morphologically derived. 
_In the course of my recently published paper I have shown 
great oo exist between the features of curvature | 
