212 
Notes. 
flower. The new perianth-leaf arises in the space left by the 
diverging halves of the labellum, but slightly behind them, whilst 
it is also decidedly internal to the two posterior sepals on each side 
of it. Probably, therefore, it represents a later development, which 
arose in the space left vacant by the splitting of the primordium of 
the labellum and the divergence of its two lobes. The flower was 
normal in all other respects. 
The second flower (Fig. 4) on the other hand exhibited a reduction 
in the number of its perianth-leaves. The two posterior sepals had 
coalesced, and had assumed a median position. The labellum was 
only very slightly developed, especially on one side, on which it bore 
a, Abortive labellum with pollen-sac. p. The two coalesced posterior sepals. 
a pollen-sac. It is probable that this pollen-sac may represent one of 
the normally suppressed postero-lateral stamens of the outer whorl. 
One of its special features of interest consists in its relatively late 
development, for though the flower was fully expanded, and the 
pollen was quite ripe in the normal anther, in this one the pollen- 
mother-cells were only beginning to become clearly differentiated. 
Possibly the arrested development of the labellum may be due to 
the appearance upon it of the sporangium; just as the normally 
vegetative leaf of Botrychium assumes the contracted appearance 
of the sporophyll of this plant when sporangia occur upon it ; or as 
the expanded petals of Nymphaea become contracted and filamentous 
as the pollen-sacs become more and more prominent. It may, how- 
ever, be urged that the reduction in size is entirely due to the lack of 
space wherein to grow, owing to the coalescence of the posterior 
