178 PRINCIPLES OF PLANT-TEEATOLOGY. 



anterior position (in some of these particular cases, 

 however, represented by two fertile stamens) with the 

 exception of being unnotched at the apex. 



Morphology of the " Corona " in Amari/llidacese. 



Oelakovsky observed phenomena of petalody of the 

 stamens in the polyanthus narcissus {N. Tazetta) which 

 are of striking importance as throwing a flood of light 

 on the morphology of the Narcissus-^owev. The salient 

 facts only will be mentioned, referring the reader to the 

 original paper for all the details. 



Fia. 132. — Sempervivum tectorum (House-leek). Stamens bearing ovules 

 on tlie ventral lameUse or upturned basal lobe. (After Von Mohl.) 



The normal anther is versatile and the stamen as a 

 whole corresponds to a peltate leaf, or, originally, to 

 a leaf with two projecting basal lobes ; supposing 

 transverse expansion of the leaf above the sinus to 

 occur, the two lobes would be carried up into a lateral 

 position ; and if, subsequently, they became united by 

 their outer margins across the face of the leaf, a cup- 

 shaped structure would result. In certain double 

 flowers of the above species some of the stamens (the 

 cause of the doubling) had become changed into struc- 

 tures which were clearly imperfectly formed perianth- 

 leaves ; in some (and this is the important point) the 

 lamina bore on its ventral surface an outgrowth, either 



