OF THE CALYX. 249 
Under ordinary circumstances, the sepals may be 
considered as the representatives of the sheath of the 
leaf (cataphyllary) or of the blade (euphyllary), the 
arrangement of the veins being different in the two 
cases; thus, in the vagina or sheath, there are gene- 
rally several large veins of about equal size, either 
convergent towards the apex, or divergent; on the 
other hand, in the blade, there is usually but one 
central vein, the midrib, larger than the rest, and the 
smaller veins come off at a less acute angle, and are 
more reticulated.’ 
Now, when phyllomorphy occurs in sepals which 
ordinarily are vaginal, it is obvious that the case is one, 
not merely of increased relative growth, but also of 
the appearance or development of an organ habitually 
suppressed; on the other hand, when phyllomorphy 
occurs in sepals which usually are lamimar in form 
and nervation, the case is one of unusual growth or 
hypertrophy, and not of the development of an organ 
habitually suppressed, so that the amount of change 
is greater in the former than in the latter instance. 
Under normal circumstances it will be found that 
laminar venation is most common in gamosepalous 
and vaginal venation in polysepalous calyces. And 
the same holds good in cases where the calyx is ab- 
normally leafy. The complete leaf development shows 
itself more frequently among the monosepalous 
! This distinction between laminar and vaginal venation is well seen 
in cases like Mussaenda, Calycophyllum, or Dipterocarpus, where the en- 
larged calycine segment has a strictly vaginal arrangement of its veins, 
very different from that which occurs in the true leaf-blades. These 
are cases, therefore, where the sheath of the leaf is unusually enlarged, 
and are not to be referred, as is often done, to metamorphosis of one or 
more sepals to perfect leaves. Prolified roses, cherries, &c., furnish 
frequently parallel cases. With reference to Mussaenda, C. Morren held 
the view that the petal-like sepal was really a bract adherent to the 
calyx, and incorporating with itself one of the calycine lobes—“ soudée 
au calice et ayant dévorée, en englobant dans sa propre masse, un lobe 
calicinal.” The Belgian savant considers this somewhat improbable 
explanation as supported by a case wherein there were five calyx lobes 
of uniform size, and a detached feather-veined leaf proceeding from 
the side of the ovary lower down (‘ Bull. Acad. Belg.,’ xvii, p. 17, 
Fuchsia, p. 169). 
