CHAP. II. INFLECTION INDIRECTLY CAUSED. 29 



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 float- 

 ing 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, nevertheless, 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 

 experiments, 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 upper 

 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 pre- 

 viously 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 been laid on the upper surface of the secre- 

 tion, 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 sur- 

 faces, by which means they were likewise drawn down- 

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



