30 DEOSERA ROTUNDIFOLIA. Chap. II. 



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

 ghind. 



In the foregoing and following cases, it is probable 

 that the vibrations, to which the furniture in every 

 room is continually liable, aids in bringing the par- 

 ticles into contact with the glands. But as it was 

 sometimes difficult, owing to the refraction of the secre- 

 tion, to feel sure whether the particles were in contact, 

 I tried the following experiment. Unusually minute 

 particles of glass, hair, and cork, were gently placed on 

 the drops round several glands, and very few of the 

 tentacles moved. Those which were not affected were 

 left for about half an hour, and the particles were 

 then disturbed or tilted up several times wdth a fine 

 needle under the microscope, the glands not being 

 touched. And now in the course of a few minutes 

 almost all the hitherto motionless tentacles began to 

 move ; and this, no doubt, was caused by one end or 

 some prominence of the particles having come into 

 contact with the surface of the glands. But as the 

 particles were unusually minute, the movement was 

 small. 



Lastly, some dark blue glass pounded into fine 

 splinters was used, in order that the points of the par- 

 ticles might be better distinguished when immersed in 

 the secretion ; and thirteen such particles were placed 

 in contact with the depending and therefore thicker 

 part of the drops round so many glands. Five of the 

 tentacles began moving after an interval of a few 

 minutes, and in these cases I clearly saw that the par- 

 ticles touched the lower surface of the gland. A sixth 

 tentacle moved after 1 hr. 45 m., and the particle 

 was now in contact with the gland, which was not the 

 case at first. So it was with the seventh tentacle, but 

 its movement did not begin until 3 hrs. 45 m. had 



