26 DROSERA ROTUNDIFOLIA. [Chap. II. 



affixed to some adjoining object, and thus left for hours; but 

 the tentacles remained motionless. 



I also carefully removed the secretion from four glands 

 with a sharply pointed piece of blotting-paper, so that they 

 were exposed for a time naked to the air, but this caused no 

 movement; yet these glands were in an efficient state, for, 

 after 24 hrs. had elapsed, they were tried with bits of meat, 

 and all became quickly inflected. It then occurred to me that 

 particles floating on the secretion would cast shadows on the 

 glands which might be sensitive to the interception of the 

 light. Although this seemed highly improbable, as minute 

 and thin splinters of colourless glass acted powerfully, never- 

 theless, after it was dark, I put on, by the aid of a single 

 tallow candle, as quickly as possible, particles of cork and 

 glass on the glands of a dozen tentacles, as well as some of 

 meat on other glands, and covered them up so that not a 

 ray of light could enter; but by the next morning, after an 

 interval of 13 hrs., all the particles were carried to the centres 

 of the leaves. 



These negative results led me to try many more experi- 

 ments, by placing particles on the surface of the drops of 

 secretion, observing, as carefully as I could, whether they 

 penetrated it and touched the surface of the glands. The 

 secretion, from its weight, generally forms a thicker layer on 

 the under than on the upi)er sides of the glands, whatever 

 may be the position of the tentacles. Minute bits of dry 

 cork, thread, blotting-paper, and coal-cinders were tried, such 

 as those previously employed; and I now observed that they 

 absorbed much more of the secretion, in the course of a few 

 minutes, than I should have thought possible; and as they 

 had b<H?n laid on the upper surface of the secretion, where it 

 is thinnest, they were often drawn down, after a time, into 

 contact with at least some one point of the gland. With 

 respect to the minute splinters of glass and particles of hair, I 

 observed that the secretion slowly spread itself a little over 

 their surfaces, by which means they were likewise drawn 

 downwards or sideways, and thus one end, or some minute 

 prominence, often came to touch, sooner or later, the gland. 



In the foregoing and following cases, it is probable that 

 the vibrations, to which the furniture in every room is con- 

 tinually liable, aids in bringing the particles into contact 



