ART III. | THE MECHANISMS OF FLOWERS. 235 
to the small supply of honey, insects with long proboscides do not 
Hy visit the flower or do so sparingly, and beetles and other insects 
which are only attracted by bright colours are also absent. 
_ Cross-fertilisation is favoured by partial separation of the sexes, 
Flowers seldom occur in which both male and female organs are 
equally developed. In the great majority of flowers either the 
stamens are fully developed and the pistil remains so short as 
scarcely to project above the honey-secreting ring (Fig. 76, 1, 2), 
or the style is long and exserted (Fig. 76, 4), and the anthers 
completely aborted: sometimes, however, flowers occur (Fig. 76, 
_ 3) in which one or two stamens are developed in addition to the 
pistil, the others being suppressed. 
I have never observed a case of self-fertilisation. 
At Lippstadt I have found Alchemilla vulgaris, L., visited by 
one of the Syrphide, Xanthogramma citrofasciata, Deg. ; on the 
Alps by three butterflies and six flies (Alpenbl. pp. 223, 224). 
Alchemilla alpina, L., A. jfissa, Giinth., and A. pentaphylia, L., 
are frequented by short-lipped insects, and do not differ materially 
in their arrangements for fertilisation from A. vulgaris. They 
show all transition-stages between hermaphrodite and purely female 
flowers; and in A. /issa, at least, among very many flowers 
bearing seed I found none with more than one stamen, so that 
flowers with more than one stamen seem to have lost their female 
~ functions (609). 
145. AcRimoniA EvpatoriA, L.—The two styles, which project 
rom the centre of the flower, are united at their base to a fleshy 
ring, on which I have not observed honey. The five to seven 
| stamens, which are inserted at the edge of this disk, bend slightly 
, inwards; their anthers, which dehisce laterally, stand on a level 
/ with the stigmas, and come in contact with them before withering 
ny bending still farther inwards. Insect-visits are scanty, and 
nust, in many cases, induce mainly self-fertilisation, for cross- 
’ fertilisation only results when the insects alight well in the centre 
of the flower. Since all the flowers are found to produce seed, 
’ self-fertilisation is doubtless quite efficient. 
| __ Eug. Warming gives a thorough description of the development 
| of the flower (762). 
Visitors : A. Diptera—(a) Syrphide: (1) Syritta pipiens, L. ; (2) Ascia 
7 yodagrica, F.; (3) Melithreptus scriptus, L. ; (4) M. dispar, Loew. ; (5) M. 
‘pictus, Mgn. ; (6) M. teeniatus, Mgn.; (7) Melanostoma mellina, L.; (8) 
Eristalis tenax, L., all fp. only ; (9) Rhingia rostrata, L., do. ; (b) Muscide : 
