Chap. 3.] Pabulum cf Plants. 31 



immenfe variety of taftes, fmelfs, &c. In the fame 

 vegetable what a variety is found ! The bark is diffe- 

 rent rn tafte from the wood, the peculiar juicas have 

 ibmething different from them both, and the pith of 

 plants affords a matter which could not have been ex- 

 peeled from their exterior properties. The root is often 

 different from the item, and the fruit from both, in all 

 their fenfible qualities. 



In whatever way the nourifhrnent of vegetables is 

 received, it may fairly be faid to confift principally of 

 water. I am inclined to believe, however, that cal- 

 careous earth, in fmall portions, may enter into the 

 compofition of at leaft many vegetables; fmce animals 

 which exift entirely on vegetable food are found to 

 have in their folid parts, the bones for inftance, a con~ 

 fiderable portion of this fubftance ; though it muft be 

 confefTed, that chemical analyfis, as far as it has hitherto- 

 gone, does not warrant us in fuppofing calcareous 

 earth to be an cflential conftituent of all vegetable 

 matter. It may be faid further, that on fcme occa- 

 ftons the addition of other matters, as of different kinds 

 of manure, adds greatly to the growth of vegetables; 

 but in whatever degree a rich foil or durig may add to 

 the luxuriance of growth, other facts feem to prove 

 that it is not effential to vegetation. It is well known 

 that many herbs fiourifh in pure water, and that pear, 

 plum, and cherry trees, planted in pure mofs, have 

 arrived at fuch perfection as to produce good fruit *. 



.Different 



* It is but fair to infert the following' fa&, which feems to fa- 

 vour the neceffity of carbonic matter to the growth and increafe 

 pf at leaft fome fpeciesof vegetables. 



f< M. Ruche rt is pcrfuaded that earth and wpter, in proper 

 proportions, form the fole nutriment of plants; but M. Giobert 

 ias clearly ftiewn the contrary ; for, having mixed pure earth of 



