Pees eee ee ee ate ee eee ee ee 
217 
The following is a summary of the results obtained with 
8. monospermum, which correspond in all essentials to those ob- 
tained with S. /aurina with the exception, that the irritability, 
and the amount and rapidity of the growth response, are not 
quite so marked. 
Owing to the slightly smaller size of the hook-tendrils of 
S. monospermum, the maximum diameter of a stem, around which 
they can form a complete coil, is also smaller, being 0.5 cm. 
A hook attached to a stem 0.6 cm. diameter was unable to 
form a complete coil, the extreme tip, as generally happens in 
such cases, bending to one side, owing to the tendency to form 
a narrower coil than was here possible, whilst after 6 weeks 
S—S A—P 
the maximum thickness was: 265 . 285. 
Unstimulated. 
ek aie, - Wea er Gos 
Loose loop of Cu wire, weight 0.2 grm. Curvature slightly 
increased. After 6 weeks. 175.210; 120.135. 
Loose loop of Cu wire, weight 0.1 grm. Curvature not increased. 
Hooks, after 6 weeks, averaged. 113.120; 100. 105. 
Loose loop of twine, weight 0.1 grm. Curvature not increased. 
Hooks after 6 weeks, averaged. 123.135; 107.112. 
Loose loop of Cu wire, weight 0.051) grm. Curvature not 
increased. Hooks, after 6 weeks, averaged. 113.128; 102 . 192. 
Hook attached in pairs, weak pull. After 6 weeks averaged. 140.178: 100.115. 
Hook attached in pairs, slightly stronger pull. After 6 weeks 
; moe . averaged. 170.198; 100.115. 
Hook attached in pairs, strong pull. After 4 weeks averaged. 238.256; 100.115. 
Loose piece of bamboo, 1 m., fitting curvature of hook fairly 
Wig : tightly, 6 weeks. 200.235; 105. 120, 
Loose piece of bamboo 2 grm., fitting curvature of hook fairly 
i . tightly 6 weeks. 265.260; 98.112. 
In this last case, as in all the experiments where tightly 
fitting rods of glass or wood are inserted in the hooks 
or hook-tendrils, there can be but little rubbing except by 
the growth of the hook tissue over the surface in contact. 
This is, however, sufficient to cause the growth to be more 
active, when the surface is rough, than when it is smooth, 
though the difference thus produced is relatively small, as 
compared with that caused by a difference in the strain or 
pressure. 
1) Is a subminimal stimulus. 
Ann. Jard. Buitenz. Vol. XV, 1. 
