208 
A hook, attached for 2 months, to a fixed support 3 mm. in 
diameter, measured at “2”: 495 590, and its breaking strain 
was 15 kilo’s, whereas an unattached one: 225 . 395, broke with 
5 kilo’s. A stem of Artabotrys, 3 metres long, with the branches 
and leaves weighed 550 grammes; therefore a single attached 
ae Xa 
metres or allowing ; as the factor of safety = 14 metres. A 
hook, such as the above, could support: 
hook, at the base of the stem, could, owing to the leverage 
which the free portion exerts, only support a considerably 
shorter length of stem than this. 
Strychnos. 
Strychnos monospermum. Migq., 8S. daurina. Wall., and 8. minus, 
have tendril like hooks, which soon became rather hard and 
woody, and are normally markedly curved. On grasping a support 
they may twine 2 or 3 times around it, and become much 
stronger and thicker, than if unattached. 
The “hook-tendrils” are intermediate, both morphologically, 
and physiologically, between hooks and tendrils. (See Trevs l. Cae 
They consist, when adult, of a thin, flexible, nearly straight, pedun- 
cular portion and a terminal, thickened, tapering, and curved, 
distal portion, the two parts having very different physiolo- 
gical properties. The physiological differentiation between the 
peduncular and distal clasping portions of the hook, of which 
Artabotrys shews the commencement , is here very marked. 
The hook-tendrils are most irritable, when nearly fully grow?, 
and partly curved. Contact, applied a little sooner or later than 
this, will generally induce the full curvature and thickening, 
but the time required is longer, than when the contact is applied 
at the period of maximum irritability. After the hook-tendrils 
‘have attained their full length, and form nearly one complete 
coul, their irritability rapidly diminishes, and disappears as $00? 
as the green colour changes to brown, and the hook-tendril 
hardens and becomes sclerotic. It is at the basal part of the 
