160 WHAT IS A PLANT? 



knows to its cost, can, by alighting on a leaf of Drosera or 

 Dio?icEa, cause it to close on itself; the leaves of Rhus can be 

 made literally to dance by throwing them into water. A similar 

 effect — i.e., a sudden movement — is seen in the irritation of some 

 stamens ; for example, those of Pellitory, Barberry, Knapweed, 

 Nettle, Periwinkle, and many others, the result being the dis- 

 charge of the fertilising pollen. Such movements are seen in the 

 caudicles of the pollen-masses of certain Orchids ; in the styles of 

 Cactus, Passion-flower, etc. ; in both stamens and styles in 

 Fuchsia, Mallow, and others ; finally, in the capsules of some 

 plants, as Geranium and Balsam, in which last case the writer has 

 seen the contained seeds scattered to a distance of over six yards ! 

 Many other examples might be cited, all showing contraction of 

 plant-protoplasm as akin to that in the animal economy. The 

 theory that plants "feel" when plucked may not be quite so 

 absurd as is supposed ; we may wake some morning to discover 

 a " something " comparable to a nervous system in the plant 

 domain, and Wordsworth may have uttered a deeper truth than 

 he imagined when he sang : — 



" 'Tis my faith that every flower 

 Enjoys the air it breathes." 



On the animal side, the Protozoa, Porifera, and some 

 CcELENTERATA, are dcvoid of any nervous system ; we meet with 

 none until we come to the Jelly-flshes, where the brilliant re- 

 searches of Mr. Romanes have discovered one to exist. Still, all 

 those devoid of it respond, like plants, to stimuli of sundry kinds. 

 Sensation, therefore, fails as a distinctive mark. 



Driven from our ground at every point, so far, let us make one 

 more attempt to find a sure standing-place ; with what success, it 

 remains to be seen. We will, as briefly as we can, select for this 

 purpose, as our " forlorn hope " — 



XL — The Nature of the Food. We have seen already the 

 general relation of plants to the mineral world. It is this : — They 

 are able to decompose simple eofupoimds, such as water and car- 

 bonic acid. From these they get their oxygen, hydrogen, and 

 carbon ; their nitrogen they get from ammonia, or its salts, these 

 being usually dissolved in the water taken up by the roots. From 



