iqiq] 



HENDRICKS— TORSION 



437 



tions in table III are correlated with the points d, e, f, g, and h on 

 the coefficient of rigidity curve in fig. 5, it is seen that the growing 

 internode does not show much rigidity until there is considerable 

 lignified tissue present. For correlation with table IV we choose 

 the rigidity curve of D-l, fig. 6, because the final diameter in this 



TABLE IV 



LiGNIFICATION TESTS; BLACK BINDWEED 



*The terminal part; the number of this internode was not determined and so is called n. 



case is nearly the same as that in table IV. The points a, h, and c 

 again demonstrate that increase in rigidity corresponds with 

 development of lignified tissue. 



Antidromous torsion 



In the studies on antidromous torsion, a glass rod lubricated with 

 vaseline was attached vertically to the apparatus, so that the frame 

 was allowed to move upward freely but was prevented by this rod 

 from rotating. At the same time the behavior of the midpoint 

 of the part of the vine used was studied by means of the mirror 

 clamp. It was found that this midpoint turned in the same direc- 

 tion as the frame would have done if it had been free to do so. In 

 the case of the bean, for example, under favorable growing condi- 

 tions the midpoint of an internode was found to twist through 



