PART III. | THE MECHANISMS OF FLOWERS. 153 
- in the middle of the flower) ; (b) .Sphegide : (3) Oxybelus sp.,s. B. Diptera 
_ —Syrphide : (4) Rhingia rostrata, L., settles sometimes in the meddle of the 
flower, sometimes on a petal, and sacks all the five drops of honey in 
succession, See also No. 590, m1, and No. 609. 
80. GERANIUM MOLLE, L.—When the flower opens, the 
divisions of the stigma lie close together so that their papillar 
‘sides are hidden. The anthers are all closed and distant from the 
“middle of the flower; the thin ends of their filaments are bent 
outwards, the inner row of stamens which stand opposite to the 
petals being bent farther outwards than the others which alternate 
with the petals. 
_ Now the outer stamens begin, one after the other, to bend 
inwards, so as to lie over the apex of the stigma, and to dehisce 
there; the flower is thus for a time male only. But even before 
the first five stamens have all dehisced, the divisions of the stigma 
begin to separate; so that the five anthers which lay over their 
Fic. 47.—Geranium molle, L. 
1—5. —Reproductive organs in successive stages. In 2, the inner whorl of stamens has been 
removed. a’, outer stamens, alternating with the petals, and provided at the base with nectaries ; a’, 
st whorl, opposite the petals, bent further out than the outer whorl when the flower opens ; 
@ s gma, 
_ apices come to lie in the angles between them, and let some part 
of their pollen fall upon the stigmatic papilla. 
| While the divisions of the stigma are expanding still more 
widely, the inner anthers, which hitherto were closed, begin to 
_ curve inwards and to dehisce. When all the anthers have shed 
their pollen, they lie partly in the angles, partly over the ends 
of the outspread stigmas, and only a little above them; so that 
insects which alight in the middle of the flower touch saithiers and 
_ stigmas at the same time, and can accomplish self-fertilisation as 
\4 swell as cross-fertilisation. 
The likelihood of self-fertilisation is thus - greater in these 
less conspicuous and therefore less visited flowers than in either 
| of the two preceding species, since anthers and stigmas come into 
immediate contact with one another early in the flowering period. 
The probability of cross-fertilisation is in consequence so much the 
