EAM 
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TO ORGANOGRAPHIC BOTANY. 149 
common petiole of the 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 lamine 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 
laming, 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 planta which - 
have sessile leaves should produce petiolar calyces, but believes 
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 laminæ 
of the leaves, he thinks it contrary to reason to suppose that this 
is really their mode of formation in some of those instanoes 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 Rose 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 laminæ 
of ‘the leaves and that the ovules bear the same relation to them 
as the buds on the margins of the leaves of Bryophyllum to the 
leaves of that plant. The monster carpels of the Columbine, figured 
