ITS NORMAL STRUCTURE. 



31 



theory of the ' transformation of the leaves into the floral organs,' * to which allu- 

 sion has already been made ( 25). When the bud is developed into a branch, 

 instead of a flower, the leaves are usually arranged in a simple spiral line. This 

 spire may be broken up into equal circles or whorls, from causes to be hereafter 

 explained. In either case the leaves of one spire, or circle, do not issue from the 

 stem at points exactly over the leaves of the next circle below, but over the inter- 

 vals between them. 



62. This simple normal structure of the flower is, however, subject to many 

 apparent exceptions, so that few, comparatively, are found perfectly conformable 

 to it. Of these few the order Linaceae affords good examples. In the flax 

 (Linum) the flower is built upon the normal plan, consisting of 5 sepals, 5 petals, 

 5 stamens, and 5 pistils (each with 5 double carpels), all alternating with each 

 other, according to the diagram (Fig. 5 ; 1 ). 



FIG. 5. Plan of flowers ; 1, oi'a regular and symmetrical flower, as the flax (Linum) ; 2, 

 of the cherry, showing the four whorls of stamens ; 3, of the primrose, showing the position 

 of the suppressed row of stamens; 4, of the Samolus, showing the position of the 5 abortive 

 stamens; 5, of a labiate flower, as the hemp-nettle (Galeopsis), where one stamen and one 

 carpel is wanting ; 6, of a cruciform flower, as mustard, where the stamens are in two 

 whorls, two of those in the outer whorl and two carpels being suppressed. 



63. If, with tliis adopted standard, we compare the numerous 



* This theory was first suggested by Linnaeus, the founder of Systematic Botany, and sub- 

 sequently by Wolff and Goethe. After having been long unheeded by botanists, it has at 

 length been revived by modern writers of the highest merit, and shown to be perfectly coin- 

 cident with facts. ' The adoption of this theory, accordingly, has given a new aspect to 

 botany, and rendered it one of the most philosophical and inductive of the natural sciences.' 

 See Gray's Bot. Text-Book, Chap VIII, where this theory is clearly stated, and richly illus 

 tratfld. 



