205 
the numbers in brackets being the averages from similar un- 
touched hooks. From this and from the data subsequently given, 
it will be seen, that the relatively most marked growth in thick- 
ness takes place in segment “2”, being less in segment “1”, 
and least in segment “3”. 
The following data are the results of experiments made to 
ascertain more particularly the response, which each part of the 
hook makes to stimulation. To do this satisfactorily, the sti- 
mulus should be by contact and rubbing, the action of which 
is localized, whilst the setting up of any marked strain in the 
hook, affecting it as a whole, is to be avoided. This is best 
done, by attaching to different parts of separate hooks loose 
loops of twine, which, being relatively light (0.39 gm.), act almost 
entirely by contact stimulation. The stimulus being a weak 
one, it must be allowed to act for a period of 4 weeks to 
obtain distinct results. 
Artabotrys Blumei. Hook. 
S54? 3-8 4-P 8-5 A—?P 
Loop around “1” 10 hooks averaged 185.310; 135.240; 85.155 
between “1” and “2” ” ” 190. 285; 185.270; 95.160 
” beyond middle of ‘9” Pee ” 170. 280; 155. 260; 105.170 
” at point measured in “2” y 9» " 185.300; 170.275; 115.190 
” on tip of “3” yoy " 160.975; 125.230; 95.170 
Similar untouched hooks he” ; 155.260; 180.240; 85.160 
Such a stimulus, applied to “1”, causes only a very slight 
thickening, restricted to that area; applied to “2”, the thicke- 
ning is much more marked, and takes place all over the hook, 
but mainly in the region stimulated; applied to “3”, the thicke- 
ning is very slight, and is most marked in the region directly 
stimulated. The increase in thickness of hooks, with loose loops 
of string, weighing 0.4 grammes, attached to «2", is much less, 
than in hooks attached to a fixed support. 
« eq? 
s—S A—P S—S A— 
Attached to a fixed support 945.300; 245 . 325; eh ga 
Loops of string attached to “2” 185.290; 170.295; 105.1 
Similar untouched hooks 180. 280; 150.275, 100.155 
It will be seen, that in the first case, where the hook is sub- 
jected to strain, the growth is fairly evenly distributed ct 
i d e the stimulus 
the whole hook, but that, in the 2"4 case, wher 
After 3 weeks. 
