14 DROSERA ROTUNDIFOLIA. Cnar. I. 
secretion, so that when the leaves are lifted out, long 
ropes of extremely viscid fluid hang from them. Some 
acids, on the other hand, do not act in this manner. 
Increased secretion is not necessarily dependent on 
the inflection of the tentacle, for particles of sugar and 
of sulphate of zinc cause no movement. 
It is a much more remarkable fact that when an 
object, such as a bit of meat or an insect, is placed on 
the disc of a leaf, as soon as the surrounding tentacles 
become considerably inflected, their glands pour forth 
an increased amount of secretion. I ascertained this 
by selecting leaves with equal-sized, drops on the two 
sides, and by placing bits of meat on one side of the 
disc; and as soon as the tentacles on this side became 
much inflected, but before the glands touched the meat, 
the drops of secretion became larger. This was re- 
peatedly observed, but a record was kept of only 
thirteen cases, in nine of which increased secretion was 
plainly observed; the four failures being.due either to 
the leaves being rather torpid, or to the bits of meat 
being too small to cause much inflection. We must 
therefore conclude that the central glands, when 
strongly excited, transmit some influence to the glands 
of the circumferential tentacles, causing them to secrete 
more copiously. — 
It is a still more important fact (as we shall see 
more fully when we treat of the digestive power of 
the secretion) that when the tentacles become inflected, 
owing to the central glands having been stimulated 
mechanically, or by contact with animal matter, the 
secretion not only increases in quantity, but changes 
‘its nature and becomes acid; and this occurs before 
the glands have touched the object on the centre of 
the leaf. This acid is of a different nature from that 
contained in the tissue of the leaves. As long as the 
