322 On the Roots dijferivg in each Soil. 



forms the new wood, as I have before shown in NicholsonV 

 Journal, vol. xxxiii. p. 234. The tap-root collects the juice?' 

 from a lower !,tr:it.a from tlic s'ti!)soil : and Ihcre, I 'doubt not, 

 much of that which conii>letes the hark is taken, besides tlw 

 iiiatter of the pollen, which is most evidently I'ormed here, since 

 T have traced it from hence to the parts adjoining the bark, aud- 

 from that place to the. hud at the time it is taking- in its .seeds and 

 pollen, when fixed in it.s cradle in tlic bark. I'he juices thus 

 obtained from the .substrata, and running in the tap-root, often- 

 show by their .strange colours th.e different kinds of liquids they 

 draw from the earth : Irnm the side roots no juices come bur 

 an in.spissated colourless licpiid, but in the tap-root it is often so 

 deeply tainted with colour as to dye th.e wood the whole way if 

 runs. I base by me three spcchnens of this : — one a beautixv.l 

 lead tint, one a bright yellow, and one a light green : the latter 

 I talie to be copper, er;p.?cially as it killed the tree. The yellow 

 was probably sulphur ; but the iirst had the appearance of a 

 bright and shining paint, highly varnished. After the tap-root 

 may be ranged the radicula : and this is the principal part that 

 really draws in the nouvishmcn.t the plant requires ; and by tlieii' 

 number we may fairly judge what cjuantity of matter the tree 

 takes in from the root: they are formed in a curious manner, 

 rounded at the end and without rind, and more intended ap- 

 parently to suck up the moisture, than take it in as the hairs. 

 I may here observe, that when it is designed to take in juices 

 fi-om the atmosphere, the instrument made use of by Nature re- 

 sembles a blow-pipe, though with many valves. But when the 

 nourishment is to be drawn from the earth, the instrument is a 

 round figure like a diminutive sponge about 2-lOths of an inch 

 in length, but vvhicli has also several valve.s to complete it ; see 

 Plate VII. fig. 1 . Besides the radicula there is another sort of small 

 root, which I call s. fibre: it is blunt, with an interior vessel often 

 pnjecthig beyond the bark: see fig. 2. ' Next to this are the hairs, 

 which arc rarely discovered of more than two sorts; see fig. 3. 

 Cut the liairs appear to me to be merely an occasional addition, 

 when a dry season requires more moisture.-r-l have now shown 

 how the root receives the liquids from the earth ; it may there- 

 fc>re be easily conceived that the quantity of matter it takes in, 

 must be proportioned to the vumbf-.r of radicula, Jlbri^s and hairs, 

 it possesses, and not to the sixa ^of its middle roui. 



This prefaced, I shall now show that the sand j)lants, which 

 take so much nutriment from the leaves, though often large in 

 the middle (as the turnip), have a totally denuded root, with very 

 few radicles and no fibres ; they have long tapering roots lessen- 

 hig by degrees to a point ; they have a few side roots rarely 

 graced with radicula. Sec the turnip -radish^ carrot, chamomile, 



urtica 



