REGULAR PELORIA. 225 
corolla. Arwm maculatum has likewise been met with 
provided with a genuine perianth as in Acorus and 
other Orontiads. The unusual development of the 
sexual organs in diclinous flowers has been alluded to 
under the head of heterogamy, and other cases where 
the symmetry of the flower is rendered regular, by the 
development of parts ordinarily suppressed, will be 
found in the chapters relating to deviations from the 
usual number of organs. 
This change, or rather this persistence of a form that 
is usually transient, is generally accompanied by some 
other alterations. Change of direction, as has been 
already mentioned, is one of the most common of 
these ; separation of the petals (Antirrhinum, Verbascum, 
&c.), and even their appearance in leaf-like guise, are not 
infrequent (Delphinium, Antirrhinum, Verbascum, &c.) 
At other times multiplication or increased number of the 
whorls of petals takes place, often, but not always, at the 
expense of the sexual organs of the flower. Perhaps 
even more frequent is the increased number of parts 
in the same whorl in cases of regular peloria ; thus, in the 
Pelargoniums before alluded to, the parts of the flower 
are frequently regulated by the number six instead 
of five. 
This form of peloria is most generally met with in 
flowers that are placed at the end or in the centre of 
the inflorescence, or in such flowers as occur singly at 
the end of the flower-stalk, as in Tropewolum, Viola, &e. 
It would hence seem as if the freedom from pressure 
or restriction on one side allowed the flower to develop 
equally in all directions, and thus to produce regularity 
of form. | 
It is obvious, from what has been before said, that 
the process of fertilisation is in many cases interfered 
with and altered by the change in the conformation 
of the flower. 
From overlooking the occasional existence of this 
form of peloria, new genera have sometimes been 
formed on insufficient grounds. The genus Aceran- 
| 15 
