14 DROSERA ROTUNUIFOLIA. CHAI-. I. 



secretion, so that when the leaves are lifted out, long 

 ropes of extremely viscid fluid hang from them. Somo 

 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 



