‘parr iu.) |THE MECHANISMS OF FLOWERS. NG 
Orv. CISTINEZ. 
45, HELIANTHEMUM VULGARE, L. (Sauerland).—The flower 
has three sepals, five petals which spread out to face the sun, and 
“many more than 100 stamens whose anthers mature simultaneously 
with the large capitate stigma. The stigma slightly overtops the 
anthers, which at first stand close around the centre of the flower, 
but move outwards when touched, dusting the insect that touches 
them with pollen. The result of this irritability of the stamens is 
that the flower is most conveniently approached from the outside, 
2¢. from the corolla, by the first visitor, and at least as conveniently 
from the centre by subsequent visitors. If an insect which has 
‘been dusted with pollen in the first flower alights in the middle of 
the next, it always effects cross-fertilisation. In default of insect- 
visits, self-fertilisation results in the closed and slightly nodding 
flowers. The flower contains no honey, for which the excess of 
pollen is some compensation. 
Visitors: A. Diptera—Syrphide: (1) Helophilus pendulus, L.; (2) 
Syrphus pyrastri, L.; (3) S. ribesii, L.; (4) Melithreptus scriptus, L. ; 
(5) M. teeniatus, Mgn. ; (6) Ascia podagrica, F., all fp. B. Hymenoptera— 
Apide : (7) Apis mellifica, L. $, ab. ; (8) Bombus muscorum, L. § ; (9) Halictus 
oo K.?; (10) Andrena fail vierun; K.@,allep. C, Coleoptera—Ceram- 
bycide : (11) Strangalia nigra, L., devouring the anthers. 
On the Alps I have found H. vulgare visited by fifty-three 
‘Species of insects ; the small-flowered H. alpestre by fourteen. They 
were mostly Peers Apide, and Coleoptera, but in part also 
Lepidoptera (609). 
| Most North American species of Helianthemum produce, in 
_ addition to the ordinary flowers, much more numerous cleistogamic 
ones. The same occurs in the case of H. Kahiricwm and H. Lippii 
in Egypt (531). 
The flowers of H. guttatum only open in the morning and 
close after a few hours, fertilising themselves if cross- fertilisation 
has not meanwhile taken place. The same is the case in H. vil- 
losum, Thib., H. eh a ong? L., Cistus hirsutus, L., and C. villosus, 
LL. (12). 
Lechea, L., also bears cleistogamic flowers (399). 
Orv. VIOLARIEZ. 
46. VIOLA TRICOLOR, L.—The peculiar arrangement of Viola 
' Was in substance elucidated by Sprengel. Hildebrand subsequently 
|} drew attention to the lip-like valve of the stigmatic cavity, by 
