STRUCTURE OF A TENDRIL 25 



up. Allow the preparation to remain in place, readjusting daily 

 to take up growth in length of organ if it is not mature. The 

 portion of the tendril between the base and the point at which 

 it is fixed to the instrument will be thrown into coils exerting a 

 pull of 1 5 to 30 g. on the dynamometer. 



FIG. 10. Dynamometer attached to Passiflora to measure contractile force and 

 also strength exerted in the formation of the free coils. ./V, support. L, fixed arm of 

 dynamometer. B y hinged arm. E, hook for attachment. 6", spring. F, scale, 

 D, portion of scale reading amount of tension. 



38. Structure of a Tendril. Cut out the most highly sensi- 

 tive portion of a tendril of Passiflora or other convenient species 

 and kill quickly in acetic alcohol. Imbed by the usual methods 

 in paraffin and cut longitudinal sections. Stain with differential 

 colors. Compare the structure of the same kinds of tissue in the 



