122 TENDEIL-BEAEEES. Chap. HI. 



from one locality alone, viz. Hampshire ; and it is not 

 improbable that plants growing under different condi- 

 tions might have their leaves a little more or less 

 changed into true tendrils. 



Whilst the plant is quite young, the first-formed 

 leaves are not modified in any way, but those next 

 formed have their terminal leaflets reduced in size, 

 *nd soon all the leaves assume the structure repre- 

 sented in the following drawing. This leaf bore nine 

 leaflets ; the lower ones being much subdivided. The 

 terminal portion of the petiole, about 1J inch in 

 length (above the leaflet /), is thinner and more 

 elongated than the lower part, and may be considered 

 as the tendril. The leaflets borne by this part are 

 greatly reduced in size, being, on an average, about 

 the tenth of an inch in length and very narrow ; one 

 small leaflet measured one-twelfth of an inch in 

 length and one-seventy-fifth in breadth (2*116 mm. and 

 339 mm.), so that it was almost microscopically minute. 

 All the reduced leaflets have branching nerves, and 

 terminate in little spines, like those of the fully de- 

 veloped leaflets. Every gradation could be traced, 

 until we come to branchlets (as a and d in the figure) 

 which show no vestige of a lamina or blade. Occasion- 

 ally all the terminal branchlets of the petiole are in 

 this condition, and we then have a true tendril. 



The several terminal branches of the petiole bearing 

 the much reduced leaflets (a, b, c, d) are highly 

 sensitive, for a loop of thread weighing only the one- 

 sixteenth of a grain (4*05 mg.) caused them to become 



