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Show 30 DROSERA ROTUNDIFOLIA. CnAI1 • II. prominence, often came to touch, sooner or lat r, the gland. . . . In the foregoing and following cases, It 1s probable that the vibrations, to which the furniture in every room is continually liable, aids in bringing the particles into contact with the glands. But as it was someti1nes difficult, owing to the refraction of th secretion, to feel sure ~ hether the particles were in con tac.t, I tried the following experiment. Unusually minute particles of glass, hair, and cork, were g ntly 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 particl s were then disturbed or tilted up several times with a fine needle under the microscope, the glands not being touched. And now in the course of a f w minutes almost all the hitherto motionl ss tentacles began to move; and this, no doubt, was cause l by on ncl or some prominence of the particl s having come into contact with the surface of the glanas. But as the particles were unusually minute, the mov m nt was small. Lastly, some dark blue glass pound d into fine splinters was used, in order that the p ints of th particles might be better distinguish d when immersed. in the secretion; and thirteen such parti 1 s wore placed in contact with the dep nding and th r f r 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 cl arly saw that the particles touched the lower surface of th gland.. A sixth tentacle moved after 1 hr. 45 m., and th particle was now in contact with the gland, whi h was not the case at first. So it was with the s v nth tentacle, but its movement did not begin until 3 hrs. 45 m. had CHAP. II. INFLECTION INDIRECTLY CAUSED. 31 elapsed. The remaininoo- six tentacles never moved as long as they were 0 bserved . and th . 1 . ' e particles apparent y never came Into contact with the surf of the glands. . aces Fro. m. these experiments we learn that part I'c 1e s not containing soluble matter when placed on 1 d f h ' g an s, o ten cause t e tentacles to begin bendino- 1·n th f . o e course of ro.m . one to five minutes.' and that I·n su ch cases t h e particles have been from the first in contact with the bsu rf.a ces of . the glands. When the te n t ac 1e s d o not egin moving for a much longer time, namely, from hh alf anb hour to three or four hours ' th e par tI' c l es ave e~n slowly brought into contact with the glan.ds, either b~ the secretion being absorbed b th particles ~r bY: Its gradual spreading over the:, to~ gether With Its consequent quicker evaporation hW hen the tentacle. s do not move' at all' the part I' c 1e s. ave never come Into contact with the gland s, or I.n som· e cases .t h. e tentacles may not hav e b een I.n an ~ct~ve condition. In order to excite movement it is Indispensable that the particles should actually r:st on :he glands ; for a touch once, twice, or even thrice repeated by any hard body is not sufficient to excite movement. Anothe~ e~periment, showing that extremely minute particles act on the glands when immersed in wa.te.r ' ma y h ere b e gi·v en. A grain of sulphate of quinine was added to an ounce of water, which was n?t after~~rds filtered; and on placing three leaves in ninety m Inims of thI' s fl U·i d, I was much surprised to :find that all three leaves were greatly inflected in 15 . for I kne w fr.o m previ·o us tn.a ls that the solution dmoe. s' not act so quickly as this. It immediately occurred to me that. the particles of the undissolved salt which were so hght as to float about, might hav;, come |