On the Physiology of VegetMes. 405 



the exertion of that force by v/hich they resist putrescence; for 

 the absorption of atmospheric matter, its conversion into nutri- 

 tive fluid, and the transmission of those jnices of the bodv, is in 

 vegetables effected bv a constant absorption of the external sm - 

 face. And in plants which increase indehnitelv (for though I 

 hava been able to trace ihe stopiiage of the yearly rous of wood, 

 yet I never have seen the ycaiLy shoot miss), they do not, like 

 the animal body, lose on one side what they gain on the other. 

 Still the internal parts change their condition : it is true the old 

 and useless parts are thrown out, as I have shown in the new 

 formed bark and wood; but the (|uantity of wood is still renewed 

 in the new shoot each season, and the extension of the tree is 

 increased, and increases in this wav as long as life endure- ; 

 though in extreme old age it geneialhj loses, by wind and ac- 

 cidents, on the north and east sides what it gains by new shoots 

 in the south and west. 



However feeble and minute the parts of an embryo may be, 

 we can certainly, in vegetables, trace it nearer the beginning of 

 life than in animals: still it has its origin in the parent tree; 

 still it takes its line of life and female flower from the original 

 seed, and from them receives its vital impulse; both have parti- 

 cipated in the existence of other living beings, and exercised 

 the functions themselves. Thus then the line of life and tlie fe- 

 male germ are the parts which more particularly support ;ind 

 convey life in the vegetable, and continue invarialjly from plant 

 to plant; and, like all organized beings, are produced bv genera- 

 tion, grow by nutrition, and are destroyed by decomposition, 



I have noticed that at fig. 6, DD had the appearance of 

 pollen between the seeds, being exactly like that whicli shows 

 itself in the ulbiirniim. There is still something obscuie in the 

 first growth of this powder, as I have never yet been able to say 

 " I saw it grow," as I have certainly and most truly done the 

 seeds and flowers. Therefore there is sonictliingmore tn be dis- 

 covered in this part: all that shows it passing into the seed- 

 vessel and into the stamen, is as complete as investigation can 

 make it; but its first forming is defective : it is in the first shoot- 

 ing of the germ of a tree from its seed this must be sought, 

 and probaijly its beginning may be traced in one of the inner 

 folds of the radicle, both in the tap root and side rooli. It will 

 appear uncommonly stupid that, taking uj) a fresh tree every 

 week or less, for four years together, I should not' have traced 

 all it contains. But 1 know not how it is, I nevor can alleiul 

 to more than one suitject at .i time ; and then all that m:iy ap- 

 pear, besides the matter sought at that mon)ent, i^ a dend letter 

 to me. This is intolerably ybo/ii/i ; — still, perhaps, it causes 

 me, by confining my attention, to fix it more completely on the 

 C c 3 object 



