60 
POPULAR SCIENCE REVIEW. 
wlien a shoot grows through, branching twigs, its revolving 
movement soon brings the tendril into contact with some 
twig, and then all three toes bend, and after several hours 
seize fast hold of a twig, exactly like a bird when perched. 
Of all the species of Bignonia examined by Mr. Darwin, 
B. Capreolata seems to offer the most curious points for 
observation. 
The tendril consists of five branches, apparently repre- 
senting two pairs of leaflets and a terminal one. Each branch 
is bifid or trifid, the points being blunt, but hooked. The 
tendrils revolve in an apparently capricious manner, sometimes 
not at all, or very slightly, but at other times they describe 
large regular ellipses. A remarkable fact about them is, that 
although they bent round sticks, the tendrils again loosed it, 
sometimes repeating the operation three or four times, recoiling 
from it “ in disgust,” and then straightening themselves. The 
tendrils, moreover, avoid the light, and when a rough post with 
crevices is given to them, the claws of the tendrils crawl into 
them. But the substance best adapted to the plant is evi- 
dently of a fibrous nature, for when — - 
“ Cotton wool or flax was placed in the proximity of the tendrils, the hooked 
points caught the fibres ; which, from the excitement they produced, caused 
the hooks to penetrate and curl inwards, so that they securely grasped one 
or two or a small bundle of them. The tips and inner surfaces of the hooks 
now begin to swell, so that, after a few days, they are converted into whitish 
irregular balls, rather above the l-20th of an inch in diameter, and formed 
of coarse cellular tissue, which sometimes wholly enveloped and concealed 
the hooks themselves. The surfaces of these balls secrete some viscid resinous 
matter, to whichdhe fibres of the wool, &c., adhere .... As the whole surface 
of the ball continues to grow, fresh fibres adhere and are enveloped;” 
So that a ball with, between fifty and sixty fibres of flax, 
crossing at various angles, all imbedded more or less deeply, 
were seen by Mr. Darwin. From these curious discoveries, 
it is deduced that although this Bignonia can occasionally 
adhere to smooth cylindrical sticks, and often to rugged bark, 
yet its tendrils are specially adapted to climb trees clothed 
with lichens, mosses, or with Poly podium incanum ; which 
Prof. Asa Gray says is the case with the forest-trees where 
this Bignonia grows. 
u Finally, it is a highly remarkable fact that a leaf should become 
metamorphosed into a branched organ which turns from the light, and 
which can by its extremities either crawl like roots into crevices, or seize 
hold of minute projecting points ; these extremities subsequently forming 
cellular masses which envelop by their growth the finest fibres, and secrete 
an adhesive cement.” 
