CH. II.] THE ROOT. 53 



the root ; that in contact ^vith the roots of peas is 

 also mucilaginous, and smells veiy strongly of that 

 vegetable ; and the freshly up-turned soil where 

 cabbages have been growing always smells offensively. 



In addition to this, every gardener knows that the 

 vigour and luxmiance of a crop is influenced remark- 

 ably by that which immediately before pre-occupied 

 the ground on which it is growing, and this does not 

 arise entirely from the previous crop having robbed 

 the soil of constituents requu'ed by its successor, but 

 from that crop ha^'ingleft something offensive. Thus 

 brassicas will not grow healthily upon soil where the 

 immediately previous crop was of the same tribe, but 

 if the ground be pared and burnt they will grow Iilxu- 

 riantlv ; and the same occurs to crroimd exhausted bv 

 strawberries : ^ if it be burnt and manured, straw- 

 berries will grow as vigorously as upon fresh gi'ound, 

 but they will not do so if manure only is applied. It 

 has also been observed that the roots of plants placed 

 in water give out their characteristic flavours to the 

 liquid, but on this, as evidence that they emit excre- 

 ments, no great rehance can be placed, for some of the 

 roots during removal from the soil must be wounded. 



The fact that the roots of plants do give out peculiar 

 and varying matters to the soil which sustains them, 

 aids to explain why one rotation of crops is superior 

 to another, as well as why fallovsing is beneficial. 



Fallowing gets rid by decomposition of any offen- 

 sive excrementitious matters, as well as accumulates 



