SYMMETRY OF THE FLO WEE. 89 



through horizontally, when all the whorls will appear projected on the same plane ; 

 and the relative positions of the organs thus displayed is termed a diagram (fig. 469). 

 Inequality of development necessarily interferes with symmetry of form (corolla of 

 Heartseas^ fig. 170; Oytisus, figs. 253,254; Tropceolum, fig. 210) ; this inequality is 

 frequently caused by the cohesion of parts, as in the bilabia.te monosepalou.s calyx 

 of Lamium (fig. 208), in the bilabiate corolla of Snapdragon (fig. 285), of Linaria 

 (fig. 286), Lamium (figs. 278, 279), in the inonadelphous androeciuin of Mallow 

 (fig. 310), diadelphous of Lotus (fig. 312), didynamous of Snapdragon (fig. 305), 

 tetradynamous of Wallflower (fig. 306) ; in the ovary of Snapdragon, the pistil of 

 Orchis, &c. irregularities which are usually accompanied with nectariferous glands 

 (Heartsease, Wallflower, Centranthus, Honeysuckle, Snapdragon, Linaria, &c.). In 

 Linaria (fig. 286) the calyx is monosepalous with five unequal divisions, the corolla 

 is monopetalous with two unequal lips, of which the upper represents two petals, 

 and the lower three, of which the centre one is prolonged below into a subulate 

 spur ; there are four stamens, of which the two longest are situated between the 

 central and the two lateral petals of the lower lip ; the two others, which are 

 shorter, are opposite the fissures which separate the two lips ; at the base of the 

 upper lip a filament represents the fifth stamen. In certain, circumstances all the 

 petals of Linaria are developed like the centre one of the lower lip ; the whorl is 

 then perfectly regular, and presents a corolla with five lobes, and five equal spurs 

 between them (fig. 469 bis}. At the same time, the filament at the base of the 

 upper lip develops into a stamen like the four others, which latter, usually unequal, 

 become precisely alike, so that the flower is furnished with five symmetrical stamens : 

 to this metamorphosis the name of Peloria has been given, which, according to the 

 theory adverted to, would be regarded as a reversion to the normal state of the 

 plant. Violets are also sometimes regular ; sometimes presenting two opposite 

 spurred petals, or three, or even five such ; when the symmetry of form is esta- 

 blished in the three first whorls. 



Cohesion or sympliysis, whether congenital or the result of growth, destroys the 

 symmetry of disjunction by effecting either the cohesion of the leaves of the same 

 whorl, or the cohesion ] of one whorl with another ; as in monosepalous calyces, 

 monopetalous corollas, monadelphous, diadelphous and polyadelphous stamens, and 

 compound ovaries ; also in flowers with inferior ovaries (Myrtle, fig. 381 ; Saxifrage, 

 fig. 382), and with monopetalous staminiferous corollas (Belladonna, fig. 294) ; in 

 calycifloral (Peach, fig. 368) and gynandrous flowers (Orchis, fig. 188 ; Aristolochia, 

 fig. 318). 



Cohesion also masks numerical symmetry, by causing a compound organ to 

 appear simple, as in the monosepalous calyx, the monopetalous corolla, the com- 

 pound ovary, &c. ; and it destroys the symmetry of position, as when the carpels are 

 enclosed in the receptacular tube (Quince, fig. 215), or in causing the andrcecium to 

 appear above the level of the pistil (Orchis, fig. 188 ; Aristolochia, fig. 318). 



Multiplication consists in the repetition of the same whorl ; thus, Berberis has 



1 In English works, the term cohesion is con- same whorl ; adhesion, to the union of the organs of 

 fined to the union of two or more organs of the different whorls. ED. 



