2GO DROSERA ROTUNDIFOLIA. CHAP. 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 He-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 lea/ 



