Cuar. XI. GENERAL SUMMARY. 275 
ness of the leaves appears to be wholly confined to 
the glands and to the immediately underlying cells. 
Tt was further shown that the motor impulse and other 
forces or influences, proceeding from the glands when 
‘ excited, pass through the cellular tissue, and not along 
the fibro-vascular bundles. .A gland sends its motor 
impulse with great rapidity down the pedicel of the 
same tentacle to the basal part which alone bends. The 
impulse, then passing onwards, spreads on all sides to 
the surrounding tentacles, first affecting those which 
stand nearest and then those farther off. But by.being 
thus spread out, and from the cells of the disc not 
being so much elongated as those of the tentacles, it 
loses force, and here travels much more slowly than 
down the pedicels. Owing also to the direction and 
form of the cells, it passes with greater ease and cele- 
rity in a longitudinal than in a transverse line across 
the disc. The impulse proceeding from the glands of 
the extreme marginal tentacles does not seem to have 
force enough to affect the adjoining tentacles; and 
this may be in part due to their length. The impulse 
from the glands of the next few inner rows spreads 
chiefly to the tentacles on each side and towards the 
centre of the leaf; but that proceeding from the glands 
of the shorter tentacles on the disc radiates almost 
equally on all sides. 
When a gland is strongly excited by the quantity 
or quality of the substance placed on it, the motor 
impulse travels farther than from one slightly excited ; 
and if several glands are simultaneously excited, the 
impulses from all unite and spread still farther. As 
soon as a gland is excited, it discharges an impulse 
which extends to a considerable distance; but atter- 
wards, whilst the gland is secreting and absorbing, 
the impulse suffices only to keep the same tentacle 
