TO OEGANOGEAPIIIC BOTANY. 149 



common petiole of tbe ordinary leaves of the plant ; thirdly, the 

 monstrous calyces of the Primrose, figured in Dr. Lindley's ' Ele- 

 ments of Botany' (figs. 147 and 148), in which laminaa correspond- 

 ing with those of the leaves are seen to be developed on the apices 

 of the united sepals ; and lastly, the analogy of the ascidia of the 

 Pitcher-plant, which are acknowledged to be petioles and not 

 laminae, with the calyx of the Lavender, in which one of the sepals 

 developes a lamina or lid, which is slightly articulated with the 

 tube of the gamosepalous calyx. In relation to sepals, however, 

 Mr. Dresser thinks it highly improbable that those plants which 

 have sessile leaves should produce petiolar calyces, but beKeves 

 that the sepals may in these instances be derived either from the 

 true lamina, or from a modification of its midrib. He applies the 

 same reasoning to the origin of the petals ; but although admitting 

 the petals to be in some instances representatives of the laminae 

 of the leaves, he thinks it contrary to reason to suppose that this 

 is really their mode of formation in some of those instances in 

 which the petiole and the lamina of the leaf are thought to be 

 most conspicuously manifested in the unguis and limbus of the 

 petal. Thus, for instance, in the Sweet William and the common 

 Pink, in which these two subdivisions of the petal are most distinct, 

 the ordinary leaves are all sessile. His conclusion is, that therefore 

 " on those plants which have sessile leaves we may look for petals 

 formed of the lamina of the leaf or of its midrib, and on those 

 with petiolar leaves for those formed of the petiole." 



With regard to stamens, in which the filament is usually re- 

 garded as representing the unguis of the petal and the petiole 

 of the leaf, and the anther as analogous to the limb of the petal 

 and the lamina of the leaf, he thinks there exists no good ground 

 for such a supposition. In the transformation of the stamen of 

 the Eose there is no trace to be found of such a distinct origin of 

 its parts ; the stamen of the Poppy, in passing into the petaloid 

 condition, is wholly transformed into an exunguiculate petal ; and 

 in Tradescantia Virginica the anther is evidently a modification of 

 a portion of a petal only, while another portion is transformed 

 into the filament. It is evident therefore, Mr. Dresser thinks, that 

 where petals are petiolar bodies, the entire stamen owes its origin 

 to the petiole alone. So also in relation to carpels, he entirely 

 dissents from the opinion that they are derived from the laminae 

 of the leaves and that the ovules bear the same relation to them 

 as the buds on the margins of the leaves of BryopTiyllum to the 

 leaves of that plant. The monster carpels of the Columbine, figured 



