26 DROSERA ROTUNDIFOLIA. Cuar. IL 
many of the other tentacles. We here see clearly that 
such bodies as particles of cinder or little balls of 
paper, after being carried by the tentacles to the 
central glands, act very differently from fragments of 
flies, in causing the movement of the surrounding 
tentacles. 
I made, without carefully recording the times of 
movement, many similar trials with other substances, 
such as splinters of white and blue glass, particles of 
cork, minute bits of gold-leaf, &c.; and the propor- 
tional number of cases varied much in which the 
tentacles reached the centre, or moved only slightly, 
or not at all. One evening, particles of glass and 
cork, rather larger than those usually employed, were 
placed on about a dozen glands, and next morning, 
after 18 hrs., every single tentacle had carried its little 
load to the centre; but the unusually large size of the 
particles will account for this result. In another case 
& of the particles of cinder, glass, and thread, placed 
on separate glands, were carried towards, or actually 
to, the centre; in another case 7, in another 4, and 
in the last case only 33, were thus carried inwards, the 
small proportion being here due, at least in part, to the 
leaves being rather old and inactive. Occasionally a 
gland, with its light load, could be seen through a 
strong lens to move an extremely short distance and 
then stop; this was especially apt to occur when ex- 
cessively minute particles, much less than those of 
which the measurements will be immediately given, 
were placed on glands; so that we here have nearly 
the limit of any action. 
I was so much surprised at the smallness of the par- 
ticles which caused the tentacles to become greatly 
inflected that it seemed worth while carefully to 
ascertain how minute a particle would plainly act. 
