152 TENDRIL-BEARERS. Cuap. IV. 
thin twig. Tendrils which have caught nothing, spon- 
taneously curl up to a close helix after the inter- 
val of several days. Those which have curled round 
some object, soon become a little thicker and tougher. 
The long and thin main peduncle, though sponta- 
neously moving, is not sensitive and never clasps a 
support. Nor does it ever contract spirally,* although a 
contraction of this kind apparently would have been of 
service to the plant in climbing. Nevertheless it 
climbs pretty well without this aid. The seed-capsules 
though light, are of enormous size (hence its English 
name of balloon-vine), and as two or three are carried 
on the same peduncle, the tendrils rising close to 
them may be of service in preventing their being 
dashed to pieces by the wind. In the hothouse the 
tendrils served simply for climbing. 
The position of the tendrils alone suffices to show 
their homological nature. In two instances one of 
two tendrils produced a flower at its tip; this, however, 
did not prevent its acting properly and curling round 
a twig. In a third case both lateral branches which 
ought to have been modified into tendrils, produced 
flowers like the central branch, and had quite lost 
their tendril-structure. 
Thave seen, but was not enabled carefully to observe, 
only one other climbing Sapindaceous plant, namely, 
* Fritz Miiller remarks (ibid. p. that the common peduncle con- 
348) that a related genus, Serjania, —_ tracts spirally, when, as frequently 
differs from Cardiospermum in happens, the tendril bas clasped 
bearing only asingle tendril; and the plant’s own stem. 
