Chap. II.] INFLECTION INDIRECTLY CAUSED. 



21 



Again, particles of coal cinder (weighing rather more than 

 the flies used in the last experiment) were placed on the 

 centres of three leaves : after an interval of 19 hrs. one of the 

 particles was tolerably well embraced; a second by a very 

 few tentacles; and a third by none. I then removed the 

 particles from the two latter leaves, and put them on recently 

 killed flies. These were fairly well embraced in 7i hrs. and 

 thoroughly after 20i hrs.; the tentacles remaining inflected 

 for many subsequent days. On the other hand, the one leaf 

 which had in the course of 19 hrs. embraced the bit of cinder 

 moderately well, and to which no fly was given, after an addi- 

 tional 33 hrs. (i.e. in 52 hrs. from the time when the cinder 

 was put on) was completely re-expanded and ready to act 

 again. 



From these and numerous other exi)eriment8 not worth 

 giving, it is certain that inorganic substances, or such or- 

 ganic substances as are not attacked by the secretion, act 

 much less quickly and efficiently than, organic substances, 

 yielding soluble matter which is absorbed. Moreover, I have 

 met with very few exceptions to the rule, and these exceptions 

 apparently depended on the leaf having been too recently in 

 action, that the tentacles remain clasped for a much longer 

 time over organic bodies of the nature just specified than 

 over those which are not acted on by the secretion, or over in- 

 organic objects.* 



Owing to the extraordinary 

 belief held by M. Zlcjrler 

 (' Comptes rendtiB.' May 1872. p. 

 122), that albuminous substances. 

 If held for a moment between 

 the fingers, acquire the property 

 of making the tentacles of 

 Drosera contract, whereas. If not 

 thus held, they have no such 

 power, I tried some experiments 

 with great care, but the results 

 did not confirm this belief. Red- 

 hot cinders were taken out of 

 the fire, an<l bits of glass, cotton- 

 thread, blotting paper and thin 

 slices of cork were Immersed In 

 boiling water; and particles were 

 then placed (every Instrument 

 with which they were touched 

 having been previously Immersed 

 in iMlllng water* on the glands of 

 Beveral leaves, and they acted In 

 exactly the same manner as 

 other particles, which had been 

 purposely handled for some time. 



Bits of a boiled egg, cat with a 

 kiilfe which had been washed lo 

 boiling water, also acted like any 

 other animal substance. I 

 breathed on some leaves for 

 above a minute, and repeated the 

 act two or three times, with my 

 mouth close to them, but this 

 produced no effect. I may here 

 add, as showing that the leaves 

 are not acted on by the odour 

 of nitrogenous substances, that 

 pieces of raw meat stuck on 

 needles were fixed as close as 

 possible, without actual contact, 

 to several leaves, but produced 

 no effect whatever. On the 

 other hand, as we shall hereafter 

 see, the vapours of certain vola- 

 tile substances and flubis, such 

 as of carbonate of ammonia, 

 chloroform, certain essential oils. 

 &c., cause Inflection. M. Zlegler 

 makes still more extraordinary 

 statements with respect to the 



