( 30 ) 



CHAPTER IV. 



THE PRINCIPLE OF ARRANGEMENT. 



m. 1-5W. fr.22MJ9 IG.2I 



Superposition and Alternation of Whorls. — It lias been 

 nlready observed that leaves are arranged on two methods, 

 either being on the same plane, i.e. opposite and verticillate ; 

 or with only one at a node, i.e. alternate. If the Gbro-vascular 

 cords passing from the leaves into 

 the stem be traced downwards, 

 those belonging to the leaves ^^ 

 situate in one and the same ver- 

 tical line always have their lower 

 extremities inserted laterally and 

 not actually confluent in that line, 

 as will be seen in Fig. 7, taken 

 from Hanstein's researches.* 



This fact is true, not only for 

 foliage and bracts, bnt also to 

 some extent for sepals and petals. 



When, however, we trace the 2.7. ^ 9J a 3.8. s. 



origin of stamens and carpels, we ^'l2 ^^ZV^^i^t^ 

 find that their cords, instead of "^"^tein). 

 being inserted separately into the fioro-vascnlar cylinder, 

 generally arise by branching, or by the so-called "chorisis" 



* De la Connexion qui exisie entre la Disposition des Feuilles et la 

 Structure de la Zone Ligneuse des Dicotyledons, Ann. des. Sci. Nat., 4^ 

 6er., torn. 8. 



