199 
the concave or convex surfaces, the growth is mainly in the 
antero-posterior plane, whereas, if on the sides, it is the lateral 
growth, which is mostly affected. Ricnarps') has shewn, that an 
injury to a plant is followed by a kind of local temporary 
fever, or tissue pyrexia, the respiration increasing and the 
temperature rising. This condition is followed by a period of 
recovery, in which the plant endeavours to repair the injury, 
and which may, when the stimulus is a lasting one, result in 
a very marked hypertrophy of the surrounding tissues, The 
same takes place, on a small scale, in the injured hook. 
Ancistrocladus Vahlit. Arn. 
The hooks are curved backwards, coiled in 11/, spirals, and 
each hook has a terminal bud at its apex. The curvature is a 
normal phenomenon, and takes place independently of contact, 
but it is slightly hastened in most cases, if the contact is ap- 
plied, when the hook is quite young. Lateral modified branches , 
arising from long erect, at first leafless, shoots, bear the 
hooks, 3 to 6 or more on each branch. The basal hook is 
the largest, the terminal one the smallest, but the hooks vary 
much less in thickness (2mm. from their bases), than they do 
in size. Without contact, the hook reaches nearly full adult size 
and curvature in from 2 to 3 weeks 7 then averaging not more 
than 2.5 cm. in length and 145 . 190 (2 mm. from base) in 
thickness. By the subsequent growth, which takes place more 
and more slowly, the hook, after becoming covered by a Corky 
layer, may after 10 weeks reach a thickness averaging: 190. 200, 
the maximal growth observed being: 935 . 255. Firmly attached 
hooks, (averaging at first: 120 . 140, after 10 weeks averaged: 
885 375, the lessened antero-posterior diameter being due to 
the flattening of the concave surface by the increasing pressure 
upon it. A hook measuring originally: 120 . 140, became afte after 
clasping a branch 4 mm. in diameter for 12 weeks: 630 . 510, 
1) Ricuarps, Annals of Botany Vol. X. 1896, Vol. XI. N®*. XLI, March 1897, 
