CHAP. II. LEAVES. 93 



number of scales or parts that constitute it. Thus #y indicates 

 that eight turns are made round the axis before any scale or 

 part is exactly vertical to that which was first formed, and the 

 number of scales or parts that intervene before this coincidence 

 takes place is 21. 



The following are some of the results thus obtained by 

 Braun, in studying the composition of the spires of different 

 plants : — 



^ in Asarum, Aristolochia, Lime tree, Vetch, Pea, the spikes 

 of all grasses. 



3- is rare in Diotyledons, and generally changes into more 

 complicated spires. It exists in Cactus speciosus, and some 

 others. 



f is the most common of all, and represents the quincunx. 

 Mezereum, Lapsana communis, Polemoniurn coeruleum., 

 Potato, are examples. 



% is also common, as in the Bay-tree, the Holly, common 

 Aconite, and the tuft of I'adical leaves of Plantago media. 



-^ exists where the leaves are numerous and their intervals 

 small. Wormwood, common Arbutus, dwarf Convolvulus, and 

 the tufts of leaves in London Pride and Dandelion, are in- 

 stances. 



2^ in Woad, Plantago lanceolata, the bi'acts of Digitalis 

 lanata. 



il in Sempervivum arboreum, the bracts of Plantago media, 

 and of Protea argentea. 



1^ was found on an old trunk of Zamia horrida, and ten 

 species of Cactus (coronarius and difformis). 



It does not, however, appear that this inquiry has led to 

 any thing beyond the estabHshment of the fact, that, beginning 

 from the cotyledons, the whole of the appendages of the axis 

 of plants — leaves, calyx, corolla, stamens, and carpels — form 

 an uninterrupted spire, governed by laws which are nearly 

 constant. No application of the doctrine appears practicable, 

 except to assist in the distinction of species, for which it would 

 be well adapted, if the determination of the series with the 

 requisite precision were less difficult ; this is shown in the fol- 

 lo-wdng instances of difference in the fundamental spire in 

 neai'ly allied species. 



