Curvature of Tendrils. 
39i 
Oct. 18, 8 a.m. Temperature 
„ 11 a.m. 
„ 5 p.m. 
„ 6 p.m. 
Oct. 19, 8 a.m. ,, 
jj 10 a.m. 
„ 1 p.m. „ 
„ 4 p-m. 
i 3 °C. 
Tension 
7 
grms. 
25° C. 
>> 
6 
? y 
24 0 C. 
5 ) 
7 
>> 
20 °G. 
8 
i8°C. 
5J 
10 
)> 
24 0 C. 
8 
9f 
34 ° C. 
>> 
9 
33 ° C. 
}> 
9 
n 
From the data given in the preceding tables it may be seen 
that the fixation of any portion of a tendril to a support does 
not induce the formation of coils in the free portion of the 
organ by transmission of a contact-stimulus. This is demon- 
strated by the fact that in a large number of experiments, 
after the tip of the tendril had clasped the dynamometer- 
hook, its extension in length made an alteration in the 
distance from the base of the tendril necessary (see Exp. IV). 
The formation of coils in the free portion of the tendril 
depends upon inequality of growth of the convex and concave 
sides, and may be induced by an artificial mechanical traction, 
or by the weight of the stem depending upon it, only when the 
period of growth of the organ has been nearly completed. The 
application of brief contact-stimuli to the irritable surface of the 
free portion of the tendril, in no wise modified the manner and 
time of the formation of the free coils. Such stimuli caused 
the formation of weak curves exerting an additional strain of 
•2 to *4 grams, which disappeared with the removal of the 
stimulus. The increase in the strain exerted upon stimulation 
speaks simply of a release of tension of the concave side and 
of a similar amount of unbalanced tension of the convex side. 
On the other hand, the decrease in the strain exerted by 
a tendril of a wilted plant must be due to the lessened tension 
of the entire organ due to an insufficient water supply. The 
decrease of strain exerted by a fully matured organ may be 
ascribed to the loss of turgidity of the parenchymatous cells. 
The lesser strain of old tendrils is due entirely to the elasticity 
of the mechanical elements which were built up while the 
organ was held in a coiled position by the turgidity of the 
D d 
