292 MR. J. C. WILLIS’S CONTRIBUTIONS TO 
anthers (fig. 11); the style is still enclosed in the tube, and its 
stigmatic papille are very short. The stamens now move slowly 
outwards and downwards, and the style grows out until the 
stigma stands at the level formerly occupied by the anthers ; its 
papille are now three or four times as long as in the earlier stage. 
The stamens now almost touch the perianth-lobes (fig. 12), and 
finally come to rest upon them (fig. 13). 
It is scarcely possible for autogamy to occur, as stigma and 
anthers are never so placed that pollen can get from one to 
the other. Pollen may fall from one flower, however, to another 
upon the same head. Out of 77 flowers examined, only 13 had 
set seed. 
Various Diptera (Syrphidx and others) were observed visiting 
the flowers; most of them confined themselves to feeding on 
pollen, as their tongues were too short to reach the honey. The 
flower appears more suited to bees or the long-tongued flies, or 
Lepidoptera. 
Cotyledon Umbilicus, Linn.—This is one of the few plants native 
in Britain whose floral biology has hitherto remained unknown. 
The plant has a tall raceme of inconspicuous scentless greenish- 
white flowers, pendent upon short stalks. The calyx is very 
small, the gamopetalous corolla tubular, about 10 mm. deep and 
3 mm. in diameter (Pl. XIX. fig. 14). The stamens, ten in 
number, are inserted on the corolla near the mouth, those opposite 
to the petals being a little higher up than the others. This latter 
point is of some importance, as the flower is obdiplostemonous, and 
so has the stigmas opposite to the long stamens (fig.15). The five 
carpels have each a large scale at the base, apparently, as in the 
rest of the order, secreting honey. This organ is reddish yellow 
in colour, and is visible, through the corolla, from outside, giving 
a reddish tinge to the base of the petals (n, fig. 14). The 
stamens dehisce when the flower opens, standing on a level with 
the stigmas, which are as yet not fully developed (figs. 15 and 
16). There is a very small space separating the anthers from 
the stigmas. In consequence of the pendulous position of the 
flower (it hangs at an angle of about 40°-80° with the horizontal), 
the anthers of the long stamens are a trifle below the stigmas. 
Later on, the latter develop, growing outwards, as shown in 
fig. 17. This brings them extremely close to the anthers. 
Young flowers stand out more horizontally than old ones. An 
insect probing the flower for honey in the young stage will 
receive pollen upon its head or proboscis, and will probably 
