BOTANY. 



Chemical 

 functions. 



Age. 



'<' granted, that there is much ingenuity and beauty in 

 Phytiulugy. t | le ot ) ler arrangement ; but we do not consider it so 

 fit for practical purposes. 



The stems of vegetables transpire an aqurous fluid, 

 and probably perform certain chemical functions ana- 

 logous to those of the leaves. We shall defer our 

 observations respecting them, until we come to dis- 

 cuss the subject in the Section appropriated to leaves 

 and their functions. 



The anatomy and physiology of the stem having 

 been thus briefly explained, there only remain a few 

 general facts to be stated, which are more immedi- 

 ately connected with it, than with any other depart- 

 ment of vegetable physics ; because almost all that is 

 known of them is derived from the examination of 

 the stem. 



The enormous magnitude of some vegetables has 

 been already noticed ; we know still less of their respec- 

 tive ages. Many plants, indeed, are so short-lived, that 

 an individual may complete many series of observa- 

 tions in the course of a life of even moderate dura- 

 tion ; and from analogy we conclude, that the same 

 general laws, differently modified, do influence the 

 whole of this class of beings. From the examination 

 f the layers of wood annually deposited, it has been 

 ascertained, that olive trees will live in favourable si- 

 tuations for 300, and oaks for 600 years. Gerardin 

 reports, that during the revolutionary war with Spain, 

 a French officer observed on the Pyrenees, in a trans- 

 verse section of a tree (but of what kind is unknown), 

 no less than 2,500 circles of wood. Gerardin very 

 properly adds, that no other authentic testimony has 

 confirmed this statement. 



It is said that Greuw, in the year 14-00, cut his 

 name on two Boabahs, and that Petiver did the same 

 149 years after. Adanson saw these names in 174-9. 

 The trees, according to his calculation, have only in- 

 creased seven feet in their circumference in the course 

 of 200 years. From which it has been inferred, that 

 as trees of the same kind sometimes acquire a peri- 

 meter of 435 feet, they live many thousand years. 

 From the above facts, we may certainly conclude 

 that our knowledge of this subject is extremely 

 small. , 



In the course of ascertaining how far a circulation 

 of sap is carried on, some interesting facts have been 

 determined by Mr Knight, and others with regard to 

 the effect of inverting stems, or, in other words, of 

 planting the superior part of the stem, and thus con- 

 verting it into a root. If the stem of a plum or 

 cherry tree, which is not too thick, be bent, and the 

 top be put under ground, while the roots are gra- 

 dually detached, in proportion ae the former top of 

 the stem becom.es firmly fixed in the soil, the branches 

 of the root will shoot forth leaves and flowers, and 

 in due time will produce fruit. Mr Knight's experi- 

 ments point out, that although the sap vessels seem 

 thus to invert their action, yet they still retain so 

 much of their original characters, as to deposit new 

 wood abve the leaf buds, being precisely the place 

 in which deposition would have occurred, had the 

 position of the plant been natural : the relative situa- 

 tion to the leaf bud is different, being above, instead 

 of belom it. 



l)r Smith's -conjecture, that new vessels are pro- 



Inverted 



Vegeta 

 (iiultinj 



Renewa 

 wood. 



gressivcly formed, appears highly probable, and will 

 do away some of the difficulties. 



Gardeners frequently perform a very simple and 

 useful operation, which is called grafting. It con- 

 sists merely in introducing a small branch into an- 

 other stock of the same genus ; the vegetative pro- 

 cess goes on, and very commonly the fruit produced 

 is extremely tine, while that from a common seedling 

 plant is unfit for use. It is difficult to explain the 

 operations of nature, perhaps impossible; but we can- 

 not help being struck with the strong analogy be- 

 tween grafting and that of transplanting teeth and 

 other parts in animals, as the late Mr John Hunter 

 sometimes illustrated in a vhimsical enough manner. 

 Miller mentions the fact, which indeed is well known 

 to practical gardeners, that those trees only can be 

 grafted on each other with success, that belong to 

 the same tribe. This resembles the inability of dis- 

 tinct tribes of animals to propagate with each other. 



The bark has a lateral productive power, when 

 only a part of it has been destroyed. This bark it 

 has been shewn deposits new wood below it. The 

 late intelligent Mr Forsyth, of Kensington Gardens, 

 applied this fact to actual practice ; and restored ma- 

 ny large forest and fruit trees, the wood of which 

 had been completely decayed, by gradually paring 

 away the old wood and bark, and by then excluding 

 the air with an excellent composition contrived for 

 that purpose. 



SECT. IV. Buds. 



No part of the vegetable structure has been ex- Bud 

 amined with more accuracy than that of buds ( Gem- 

 m(e) from the time of the faithful and diligent 

 Grew, to that of the discriminating and candid 

 Knight, and yet it is very singular that little 

 was known of their physiology until the experi- 

 ments and observations of the last gentleman were 

 made public. To him, therefore, we are indebted 

 for some of our most valuable knowledge on this 

 subject. 



A bud is that part which " contains the rudiments Definit 

 of a plant, or of part of a plant, for a while in a 

 latent state, till the time of the year, and other cir- 

 cumstances, favour their evolution." From buds, 

 then, an entire plant may be produced, if placed in 

 favourable circumstances, or only a branch, or leaves, 

 or flowers. We can, however, reckon no more than 

 two kinds, those that produce leaves, and those that 

 produce flowers, as will be sufficiently seen in the 

 sequel. There is the closest analogy between these 

 organs and bulbs ; so close, indeed, that Mirbel, and 

 some others, arrange them together. Of this we shall 

 speak more at large when treating of the origin of 

 the former. Practical cultivators mark distinct cha- 

 racters peculiar to each kind of bud. Those that pro- 

 duce leaves are small, long, and pointed ; the flower 

 buds, again, are thick, short, and round. It appears 

 probable that some unknown agents influence the 

 formation either of flower-buds or of leaf-buds, or 

 rather that some circumstances will cause the evolu- 

 tion of either of them from the same bud. A fact 

 recorded in the Linnzan Transactions in some mea- 

 sure favours this opinion. The SoldTulra grandi/lorii, 



