1 16 DESCRIPTIVE BOTANY. PART I. 



soluble short closed filamentous tubes, or sacks (fig. 130.), 

 which ultimately discharge their contents by the rupture 

 of one of their extremities. 



CHAP. VI. 



MORPHOLOGY. 



A BORT10N (115.). DEGENERATION (116.). ADHESION (118.). 

 SUPERNUMERARY WHORLS (119.). NORMAL CHARAC- 

 TERS (120.). SPIRAL ARRANGEMENT OF FOLIACEOU8 



APPENDAGES (121.). TABULAR VIEW OF VEGETABLE OR- 

 GANISATION (123.). 



(114.) Morphology. IT is an observed fact, that the 

 subordinate parts which make up the floral whorls of 

 very many plants, are symmetrically arranged round the 

 axis, and that the parts of each separate whorl are placed 

 alternately with those of the contiguous whorls. Con. 

 nected with these facts, it has been remarked, that the 

 flowers of certain species, whose parts are not symmetri- 

 cally arranged, and which do not alternate in the manner 

 described, do nevertheless occasionally assume a per- 

 fectly regular structure, by the development of super- 

 numerary parts. As an illustration of our meaning, we 

 may select the common snapdragon (Linaria vnlyaris) ; 

 in which, as well as in some other species of this and of 

 the allied genus Antirrhinum, the phenomenon we are 

 about to describe may occasionally be observed. The 

 common form of the flowers of this plant is termed 

 "personate" (fig. 131. a); the corolla is monopetal- 

 ous, and divided into two large lobes, closed in front, 

 and presenting somewhat the appearance of an animal's 

 face. The upper portion of the corolla is prolonged 

 backwards, into a tubular " spur ;" it contains four 

 stamens, arranged in pairs of unequal length (didy- 



