BRA 



wpertain to the branches, continue rc^juhrly to decline, in 

 proportion as the fediions are performed lower upon the tree, 

 until they difappoar altogether, there being at lall exhibited 

 only the appearance of the divided circles of the layers of 

 wood, which conilitute the main trunk. The connexion of 

 the branches with the trunk is, therefore, by means of a 

 cone, of which the apex is diredcd towards the cc;itiv ol 

 the tree, and the bafe correfponds with the fuperficics. 

 Fix- 4- of PLle II. in yr^rtable ^iialoniy, reprefents the ar- 

 rangement of the lij;ntouB fibres, by means of wliich the 

 orijjin of the branches is rendered of a conoid form. 



When a branch is forcibly torn from the lUm, it is com- 

 monly obfervcd to briii^ with it a portinn of a cone or pyra- 

 mid, wliicli leaves a corrtfponding dcprLlTion at tiit part 

 from whence the branch has been removed. Tliis arifes 

 from the woody fibres being moft eafily ruptured, where tiity 

 are reflected into the angle, which forms the line of jundiun 

 between the branch and the trunk. 



The fmall or fecondary bi-aiiches have precifcly the fame 

 kind of orij»iu and connexion with rcfpect to t!ie large or 

 primary branches, which ihcfe latter liave with regard to 

 the trunk. Hence every branch may be coiifidtred as a 

 parent ftem fuftaining others, which in their turn give origin 

 to new branches, and thefe again to others, as long as the 

 vegetable continues to grow. 



brandies acquire bulk by the addition of fucccfilve 

 layers of wood, in the fame manner as the trunk. See 

 Ji^'. ^. of P/ate II. in Vegelnbli Aiialowy, which is copied 

 from the delign of Duhamel, to illullrate the growth of 

 branches. The entire lignre is fiippofed to reprcfeiU a ttee 

 of four years of age, furnilhed with fevtral branches in the 

 order in which they might naturally occur. The wood\' 

 cone, N° I, having developed a bud towards a, a branch 

 vould exill in the fouVth year polTefTed of four layers of 

 wood, as rcprcftnted by a b. If another bud wore formed 

 upon the ligneous layer of the fecond year, N° 2. 2, its 

 branch in the fourth year would be compofcd of three layers, 

 as feen in c d. Admitting further, that in the third year 

 a bud was produced from the branch a b towards /', a little 

 branch would be formed which could only have two layers ; 

 and lallly, if in the fourth year, when the llgncoiIS layer 

 N° 4. 4, is depofited, another bud wtrc to grow towajds »■, 

 the branch to which it would give origiu would be made of 

 only one layer of woody fibres, as (liewn by g h. Thus, 

 the number of woody layers which compofc any branch 

 being afcertained, its age becomes knowu, and the relation 

 which this bears to the age of the parent trunk is diicovcrcd 

 by finding the woody layer upon which the apex of the 

 ligneons cone of the branch is implanted ; or, in other words, 

 obferving the point where the paralklifm of the longitudinal 

 fibres of the trunk is tirll interrupted. 



It is alTerted by Parent, " Hiftoire de I'Academie," 

 1/1 1, that the branches are nourifhed by the pith or medulla, 

 but nothing can be more erroneous : the medulla of the 

 branch does not even communicate with that of the trunk, 

 although the ligneous cone of the branch is moll freqnentlv 

 implanted upon the innermoft layer of tiie woody fibres, or 

 thofe which immediately incafc the medulla. 



Du Hamel has remarked, that the longitudinal fibres, 

 whether woody or cortical, take the direction of the cliicf 

 current of the fap : thus, if the fap be propelled in the di- 

 reAion of the trunk, (vvliich happens when, either the 

 branches hav* been originally iiiconfiderable, or have been 

 early lopped off,) the conical and woody libres prcfcrve 

 nearly a pcrpenC.ular poiition, only ftparating to give paf- 

 fagc to til? branches and immediately after recovering their 

 paralleUlm. See PLle II. in Fc^aable ^ha!cmj\ Fig. C. 



BRA 



exhibits a portion of a thick trunk, from the fide of which 

 had proceeded a fraall branch. If a large branch anfes from 

 a trunk, it neceffarilv altraAs a great portion of the lap, 

 and, in ihih cafe, the inclination of the cortical and woody 

 fibres is obliquelv towards th^t brahch, as it is rcprcfcntcd 

 bv /!>. 7. of Plats I!, in p'egetabk Anatomy. 'I'his efiedt is 

 Hill more remarkable in trees, wh.ich have been topped im- 

 mediately above the oiigin of a.young biar.ch ; for then, all 

 the I'l'.p bci.ig obliged to p:;fs towards tlie branch, the fibres 

 purfut the fv.ne direction, and hence, if a tree be examined 

 in the fpiiug, after having been thus deprived of its top the 

 preceding winter, the new lignco'.tS <ibres will be obfcr\ed 

 to crofsthc others, as appears lu.y^. 8. of Plate II. in Ve~ 

 g^lMe AiuUoi:iy. 



The courfe of the ligneous fibres determines the nature 

 and (luality of what ii called ^\\iigfam of wood. In proportion 

 as t!ie lilirei prtferve the parallel direction the grain is 

 fmooth and equal, and the wood tradable in the hands of 

 the workman, and accoi-dinglv thole trees which furnifh 

 but few or fmall branclus, fiuh a:, the different/; j, are molt 

 ulVd in carpentry : wh 11 11 ww /;&;,' iJ/'V and leveraly}-;.// /r^-ij are 

 preferred for making furniture, on account ot the various 

 difpohtlon of the fibres, and the number of large knots, 

 which produce the beautiliil divciiity ot colours obferved in 

 thefe woods. 



The branches occafion that appearance in wood, known 

 by the name of a knot : the longitudinal iilnes being di- 

 verted from their courfe, and fubjefted to compreflion, at 

 firll by the eruption of the bud, and afterwards by the 

 growth of the branch, acquire a degree of lolldity and com- 

 paftncfs unlike any other part of the vegetable body. The 

 ligneous cone of the branch itfclf generally acquires more 

 orlefs of the knotty texture ; the converfioii of the origin of 

 the branch into a knot is influenced however by fcvcial ac- 

 cidental circumftanc-s, the habit of the tree, &c. which are. 

 pointed out in another place. See KnuT. 



The branches of the vegetables with one feminal leaf diflcr 

 from the dicotyledons in this particular, that they are not 

 produced by buds, but by the longitudinal fibres turning 

 alide, and prolonging themfelvcs in a diagonal courie, until 

 they penetf^e the bark. 



After tliedclcilption- which has been given of the origin and 

 growth of the branches, it is almoll unneceflary to add, that 

 they polTcfs the fame anatomical llrufture as the trunk ; all 

 the parts which compofe tlie one are met with in the other, 

 and are difuofed wltii perfctl liniilarlty in each, as the 

 epiilermis, the parenchyma, the cortical layers, llie wood, and 

 the medulla. 



The form of the larger branches is moft frequently cylin- 

 drical, but the flcnder ones have levtral fides, or exhibit in 

 the tranfverie fi.ttion more or lefs of a polygon figure. 

 The leftion of the branches of the alilir and the orange-tree 

 is triangular, that of the Virginian poJ)hir u fquare, and in 

 the plum-tree and 'willow it is pentagonal. 



The general appearance of a vegetable, which botanilis 

 have termed the habitus, depends chiefiy upon the poiition 

 wliich the brandies and their ramifications obtain with re- 

 Ipeft to each other, and the different direftions they ailume. 

 The branches like the leaves arife in various ordei»: fome- 

 times they are oppofed to each other, as in the hazel, oak, 

 and coffee trees ; at other times they fuccced one another 

 alternately, as in the pear and apple trea, &c. They are 

 arranged in a circle round the item in the protea arg./itea : 

 in lome inllanccs tlie branches are widely fcattertd on the 

 tree, while in others, they are fo thickly fet;, that they con- 

 ceal from view the trunk and one another. The various 

 fituations of the branches depend upon that of the buds 



froiri 



