212 VEGETABLE ORGANOGRAPHY. 



If we continue to compare the roots with the branches, 

 we more readily see that they are not organs of the 

 same kind, as many authors have thought ; their origin 

 is entirely different, at least in Exogens : the branches 

 spring from a bud, which is a process continuous with the 

 bark, and which encloses the branch perfectly formed, 

 but in miniature : true roots always arise without buds, 

 and those which are produced by the bark of trees pro- 

 ceed from the lenticels, which never give origin to any 

 branch. The branches are disposed in an order which 

 is naturally regular, and analogous to that of the leaves ; 

 the roots arise most frequently without any determined 

 order, or, if there be any, it is different from that of the 

 branches; thus the French Bean has the leaves quin- 

 cunx, and its roots, placed in water, shoot out radi- 

 cules in four longitudinal rows : the Mayanthemuni has 

 two altei-nate leaves, and the radicules are verticillate 

 around the central root. This disposition of the roots 

 is subject to great variations, on account of the obstacles 

 which the soil opposes to them. I have observed, in 

 an experiment, that the roots of the same species of 

 Willow are very different from one another, as regards 

 the size, and also the disposition of the lateral radicules, 

 according as they have been grown in pure water, or in 

 that which was coloured by cochineal. 



Branches often present articulations ; roots are always 

 devoid of them. Their knots even, when they exist, 

 have only a very remote connexion with those of stems 

 and branches. 



We may also remark that roots are but little, if at 

 all, subject to some of the causes which so strangely 

 modify the appearance of stems and leaves. Thus they 

 present hardly any kind of degeneration, either in limb, 

 scale, tendril, or spine — phenomena so common in stems. 

 The junction of roots with one another, or with other 



