260 DROSERA ROTUNDIFOLIA. Cuap. X. 
tentacles, which acts on the cells at the bending place, 
but does not induce aggregation until it has reached 
the glands; these then send back some other in- 
fluence, causing the protoplasm to aggregate, first in 
the upper and then in the lower cells. 
The Re-expansion of the Tentacles—This movement is 
always slow and gradual. When the centre of the 
leaf is excited, or a leaf is immersed in a proper solu- 
tion, all the tentacles bend directly towards the centre, 
and afterwards directly back from it. But when the 
point of excitement is on one side of the disc, the 
surrounding tentacles bend towards it, and therefore 
obliquely with respect to their normal direction ; when 
they afterwards re-expand, they bend obliquely back, 
so as to recover their original positions. The ten- 
tacles farthest from an excited point, wherever that 
may be, are the last and the least affected, and probably 
in consequence of this they are the first to re-expand. 
The bent portion of a closely inflected tentacle is in a 
state of active contraction, as shown by the following 
experiment. Meat was placed on a leaf, and after the 
tentacles were closely inflected and had quite ceased to 
move, narrow strips of the disc, with a few of the outer 
tentacles attached to it, were cut off and laid on one 
side under the microscope. After several failures, I 
succeeded in cutting off the convex surface of the bent. 
portion of a tentacle. Movement immediately recom- 
menced, and the already greatly bent portion went on 
bending until it formed a perfect circle; the straight 
distal portion of the tentacle passing on one side of the 
strip. The convex surface must therefore have pre- 
viously been in a state of tension, sufficient to counter- 
balance that of the concave surface, which, when free, 
curled into a complete ring. 
The tentacles of an expanded and unexcited leaf 
