PART III. | THE MECHANISMS OF FLOWERS. 69 
Sld. =Sauerland (Warstein, Mohnethal, Briion) ; Tekl.=:Teklenburg (Herr 
Borgstette) ; Th. Thuringia (neighbourhood of Miihlberg). In all cases in 
which the locality is not specially mentioned, the observation was made near 
Lippstadt. 
Numbers placed in brackets after the names of insects indicate the length 
of the proboscis in millimetres, 
¢=male; 9? =female; § =worker. 
Orv. RANUNCULACE 4. 
1. CLEMATIS RECTA, L.—The flowers are destitute of honey. 
When they open, the stigmas are still immature, and are covered 
up partly by the stiff hairs of the pistil, and still more efficiently 
by the stamens which press closely upon them. The outermost of 
these latter soon begin to bend outwards, and their narrow anthers 
dehisce lengthwise, so that the broad connectives appear covered 
on both sides with pollen, At this time, the flowers are well fitted 
to supply pollen to insects, but the stigmas are unable to retain 
pollen with which the insect-visitors are coated. The bending 
outwards and dehiscence of the anthers now proceeds centripetally, 
and before the innermost stamens have joined the rest the stigmas 
lie fully developed in the middle of the flower. Insects which come 
at this period from other flowers and settle in the middle must 
accomplish cross-fertilisation. Bees almost always alight in the 
middle of the flower, both because they can more conveniently 
reach the stamens from the centre than from the edge, and also 
because the anthers near the centre are least likely to have been 
already emptied. The pollen-eating flies which settle at random 
on the flowers and creep about in them can produce self-fertilisation 
as easily as cross-fertilisation. In default of insect-visits, self- 
fertilisation readily takes place, for the outermost stigmas are often 
touched by pollen at the bursting of the anthers, and frequently 
part of the stigmas lie so that pollen may fall directly on them 
from anthers above. 
Since the flowers are destitute of honey, and all attractions for 
insects therefore cease with the dispersal of the pollen, their pro- 
terandrous condition has not been able to perfect itself. They are 
naturally only visited persistently by pollen-seeking insects, but 
by these in considerable abundance, owing to the large stock of 
pollen. | 
A. Hymenoptera—(a) Apide@ : (1) Prosopis signata, Pz. ¢,f.p.; (2) Andrena 
Gwynana, K. 9; (3) A. albicans, K. 9; (4) Halictus sexnotatus, K. 92; 
(5) Osmia rufa, L. 2; (6) Bombus terrestris, L. 9; (7) Apis mellifica, L. § ; 
