ON THE STEM OF TREES. 347 



disgust and tire my reader; but I may at a future time give 

 the rest. 



The pith, which I shall now turn to, I esteem merely as Pith. 

 a source of moisture to the rest of the plant when wanted : 

 it stops with every flower bud, and begins again to grow as 

 soon as the bud is past : it decreases as the strength and size 

 of the tree increases; it is the only part of the tree, that 

 has no vessels to contain liquor, for it is a net only, not a 

 bundle of cylinders. It has been said, that it is composed 

 of a great variety of figures, but this is a mistake : take it 

 out extremely thin, and most piths will be found of one 

 figure only. There are, however, a few different sorts; 

 the net of the dogwood is very curious, and the pith of the 

 juglans, and a few others differ in form. The size of the 

 pith will form a tolerable division between the tree and 

 shrub. 



I have but little to say of the root, except that I look Growth of the 

 upon it to be wholly formed of the rind, much thickened, root * 

 and perhaps a very little of the bark, but to be without 

 inner bark, to have a quantity of wood, no spiral vessels, 

 and hardly any pith. I searched in vain for the larger 

 vessels of the inner bark, till it struck me, that the want 

 of it was the reason of there never being a leaf on a 

 root. In Devon this is a trial more easily made than in 

 any other place ; and I have repeatedly been assured, that 

 roots were found with leaves, but it always turned out 

 to be a branch zohich crossed the root ; and I always found 

 it so, on dissecting it, to try the truth of the assertion. 



1 shall now close my letter with endeavouring to prove Each part of 



the truth of an observation made lone ago by that excellent est .^ m ha f 



° D ' each its parti- 



observer Linnaeus, and since so absolutely denied by many: cular partoftha 

 I mean, M that each part of the stem has, when it arrives ower * 

 near the flower stalk, its peculiar juice" for the formation 

 of each part of the flower; that the bark produces the 

 calyx of the flower; the inner bark the corolla; the wood 

 the stamen; the circle of life the pistil : an 1 that they all 

 join in forming the fruit and seed. Willdenouw says, that, 

 without having recourse to the plant, or to dissection, it is 

 at once possible to show the folly of supposing, that each 

 particular part of the plant should produce only one part of 



the 



