DR. M. T. MASTERS ON THE PASSIFLORACEÆ. . 617 
In the young state the anthers are introrse and pressed up against the sides of the 
ovary and styles, the large stigmas of which project beyond the anthers. When the 
anthers become sufficiently matured to allow of the emission of the pollen, they undergo 
a change of position: the filaments spread more or less horizontally, and the anthers 
become extrorse; so that if the flower-stalk spread somewhat horizontally, as it does 
usually, or if it be erect, the pollen is likely to be shed on the corona, the styles at this 
stage being horizontal, with their stigmas quite out of reach of the pollen. In this. 
manner the corona is often found dusted over with pollen; and in Passiflora cincinnata, 
Mast., and in other species it often happens that the stamens are bent downwards to 
such an extent as to come into direct contact with the corona (Plate LXV. figs. 4, 5). 
The outermost rows of the corona, then, appear to attract insects, the smaller threads 
proceeding from the throat of the flower-tube catch the pollen, while the membranous or 
median corona (operculum) shuts off the upper portion of the flower from the nectar- 
secreting portion at the base. The peculiar pulley-like process of the stalk of the pistil 
in some Passion-flowers, and the substitutes for it in other species, have already been 
alluded to. In all cases the object seems to be to detain the insect in its passage to the 
nectar-secreting portions, and so to enable it the more surely to be dusted over with pollen. 
Now, when a Bee visits an expanded flower, it is easy to see how the insect favours cross 
fertilization. The insect alights on the rays of the corona; and if there be pollen on 
them, some of it must naturally adhere to the hairs on the insect’s back. Moreover, 
if the insect be large, or the stamens, with their now extrorse anthers, be bent down- 
wards, as they usually are at a late stage of the expansion of the flower, it is obvious that 
the back of the insect is very likely to come into contact (nay, does so, as I have fre- 
quently observed) and thus remove some of the pollen from them. In those cases 
where, from the pendulous position of the flower (P. quadrangularis, P. macrocarpa, &c.), 
the pollen cannot fall on the eorona, which is now placed above the anthers, the pollen 
is removed by Bees in the manner just indicated. When the pollen-carrying insects 
alight on the corona of another flower it may so happen that the stigmas of that flower 
are so placed as to render them liable to come into contact with the insect, and to 
remove from its hairy thorax the pollen-grains with which it is bestrewn. The styles, 
which are erect all the time the anthers are introrse and so placed as to be liable to 
‘contaminate the stigmas, gradually assume a horizontal or even a deflexed position when 
the anthers are extrorse, or bent downwards, so as to render access of the pollen from 
them an improbable occurrence. All this may readily be seen by any one who watches 
a Humble-bee as he flies from flower to flower of any of our cultivated 
but it would seem probable, from the length of the gynophore, that in 
their native haunts the flowers of Tacsonias, for instance, are visited by some larger 
creatures than Bees. Indeed some travellers state that the honied flowers of the 
Tacsonias are very attractive to Humming-birds; and these elegant little creatures pro- 
bably act as the carriers of pollen from one flower to another. : 
In connexion with the uses of the corona, I may here mention that, according to the 
late Prof. Morren, the corona is the seat of the perfume of the flower in Passiflora 
VOL. XXVII. AN 
the operations of 
Passion-flowers ; 
