526 ANGIOSPERMAEDICOTYLEDONES 



12 mm. long and 2-3 mm. in diameter, which suddenly expands to two or three 

 times that width; a total length of about 27 mm. being attained. The throat is 

 8-10 mm. in diameter, so that a bee of the size of Osmia rufa L. $ (which Miiller 

 observed as a particularly frequent po-cltg. or nect-skg. guest) has room to creep 

 right in, and reach the nectar with its extended proboscis ; larger humble-bees, 

 on the contrary, cannot enter the flower. When the above-named bee creeps 

 into the entrance of the flower, it first touches the 2-5 lobed stigma, which 

 projects beyond the stamens, and dusts it with pollen brought from other flowers. 

 The bee then encounters the anthers, which surround the throat of the corolla, 

 and its hairy covering takes up a fresh supply of pollen. Stadler describes the 

 flowers as protogynous, but says that automatic self-pollination is not excluded 

 (' Beitrage '). 



The corollas remain persistent for a considerable time, and even assume a darker 

 rose-red colour than when the stigma and anthers were mature. The oecological 

 meaning of this is the same as in Ribes sanguineum and R. aureum. Cf. p. 419, and 

 Vol. I, p. 86. 



Visitors. Besides Osmia rufa L. 5, Herm. Miiller observed two other bees 

 (Halictus leucopus K. 5, and H. sexnotatus K. 5), both creeping entirely into the 

 flower: also a po-dvg. beetle (Dasytes sp.). 



Alfken saw the bee Prosopis hyalinata Sm., asleep in the early morning in the 

 hollow of the flower. 



I have frequently noticed in my garden the humble-bee Bombus agrorum F. j, 

 pushing the front part of its body into the flower, and inserting its proboscis far 

 enough to suck the nectar. Though cross-pollination is regularly effected in this 

 way, I have never remarked the setting of fruit. I have also seen the same 

 humble-bee as a visitor in Mecklenburg and Pomerania. 



388. Diervilla Tourn. 



1215. D. japonica Thunb. Stadler (' Beitrage ') describes the flowers of this 

 species as protogynous ; so is the var. amabilis (Francke, ' Beitrage '). 



1216. D. canadensis Willd. (=D. trifolia Moench). (Francke, op. cit. ; Loew, 

 'Bliitenbiol. Beitrage,' II, pp. 61, 63; W. J. Behrens, 'D. Nekt. d. Blttten.') This 

 species is protogynous, and possesses a nectary beset with long clavate hairs. 



1217. D. floribunda Sieb. et Zucc. This and other related species agree with 

 D. canadensis. 



389. Aucuba Thunb. 



1218. A. japonica Thunb. 



Visitors. Plateau (Belgium) noticed po-dvg. Muscids (Calliphora vomitoria Z., 

 and Musca domestica Z.). 



390. Symphoricarpos Dill. 



Flowers reddish in colour, bell-shaped, homogamous; with concealed nectar, 

 secreted, according to Delpino, by a papillose gibbosity on one side of the corolla. 

 Bonnier says that all the parts of the flower are very rich in sugar. He does 





