38 PKOSEEPINA. 



the tobacco tribe, has been singularly harmful, togethei 

 with its pungent relative, to a neighbouring country of 

 ours, which perhaps may reach a higher destiny than any 

 of its friends can conceive for it, if it can ever succeed in 

 living without either the potato, or the pipe. 



17. Being prepared now to find among plants many 

 things which are like roots, yet are not ; you may simplify 

 and make fast your true idea of a root as a fibre or group 

 of fibres, which fixes, animates, and partly feeds the leaf. 

 Then practically, as you examine plants in detail, ask first 

 respecting them : What kind of root have they ? Is it 

 large or small in proportion to their bulk, and why is it 

 so ? What soil does it like, and what properties does it 

 acquire from it ? The endeavour to answer these questions 

 will soon lead you to a rational inquiry into the plant's 

 history. You will first ascertain what rock or earth it de- 

 lights in, and what climate and circumstances ; then you 

 will see how its root is fitted to sustain it mechanically 

 under given pressures and violences, and to find for it the 

 necessary sustenance under given difficulties of famine or 

 drought. Lastly you will consider what chemical actions 

 appear to be going on in the root, or its store ; what pro- 

 cesses there are, and elements, which give pungency to 

 the radish, flavour to the onion, or sweetness to the liquor- 

 ice ; and of what service each root may be made capable 

 under cultivation, and by proper subsequent treatment, 

 either to animals or men. 



18. I shall not attempt to do any of this for you ; I as- 



