202 
was more effective as a stimulus, than a smooth one with 
doubled pressure. 
» Olax”. 
The plant described by Treub as, Olaz (sp.%), Bangkok, is 
really Roucheria Griffithiana. Planch., for which Hugonia Suma- 
trana. Miq., is also a synonym. (Boerlage). 
In hooks clasping a fixed support, the commencement of 
coiling and thickening is perceptible after the first day, under 
favourable conditions, but with less sensitive hooks, on less 
vigorous shoots, not till after 3 days. 
A loose loop of twine, weighing 0.5 grm., touching the concave 
surface, caused, after 1 week, an increased coiling of 30° as 
compared with untouched hooks, the relative thicknesses avera- 
ging out of 10 experiments: 
Attached. Unattached. 
a  —=Eeeeee 
Before contact. After 1 week. At first. After 1 week. 
Base. Middle. Base. Middle. Base. Middle. Base. Middle. 
S—S A—P S-SA—P | 8-8 A—P 8S A—P| S—s A—P S—SA—P | S—S A—P S—SA-P 
95.115; 75.80 | 115.170; 105.115 | 100.120; 75.75 | 115.145; 80.80 
The most marked increase of thickness takes place at the 
middle of the hook, close to where the contact is applied. 
The largest size , to which hooks attain, without contact 1s 
base: 295 . 310, middle: 255 . 230, being coiled in slightly 
more, or slight less, than 1 turn, whereas the adult attached 
hook forms from one to 1}/, turns. 
Kilo 
88 A—P ‘ 2 
(2). Hook. 3 months fixed tightly to support 6 mm. diam. 550 . 700 breaking aires 
ui n" W I 
(b.) NW r Wi " ” O75 4.30 w ud 9 
(c.) w# overlyear I 3g ty n 1200.900 vv ny 
(dZ.) » 4 months untouched 925.280 7 We 
The old hooks, which became attached last rainy season, at@ 
very large, and, if the support be a living branch may be 
quite coalesced with it, or may strangle it. In such old tightly 
clasping hooks, the lateral diameter is always greater than the 
