34 



ANGIOSPERMAEDICOTYLEDONES 



forwards. Insects can only obtain nectar legitimately by alighting upon the left all I 

 and pushing their proboscis under the opening on the right side of the carinal tip I 

 To prevent access in any other way, there is here an upwardly and forwardly directe( j 

 scale-like appendage. 



Only large humble-bees are able to work the flower mechanism. When th<| 

 carina is depressed the end of the style with its pollen-covered brush springs out o I 

 the opening in the carina, and a narrow canal appears, beginning just below tbl 

 carinal opening, and running past the end of the style, along the right margin o I 

 the groove in the staminal column as far as the base of the nectary. The uppe I 

 free stamen retains its position, while the nine united ones are bent downwards | 

 As the stigma is touched by the proboscis of an insect visitor before the pollen, i I 

 follows that cross-pollination is regularly effected by visits. Automatic self-pollinatioi 

 is excluded : unvisited flowers remain infertile, as already stated. 



Visitors. I saw, at Kiel, Bombus hortorum Z. $, skg. legitimately. In spit 

 of constant watching, I have but seldom observed insect-visits, and automatic self 

 pollination takes place in the large majority of cases, though Darwin was of th< 

 contrary opinion {vide supra). Some humble-bees obtain the nectar by perforation 

 I observed Bombus terrester Z. as a nectar-thief at Kiel. 



Alfken saw a bee (Megachile maritima K. ) at Bremen, and another (Osmi: 

 maritima Friese j) in Juist. Leege observed (Juist) a bee (Osmia maritima Friese $) 

 freq., skg. and po-cltg., a hawk-moth (Deilephila galii Rott), and a Noctuid (Chari 

 clea umbra Hfn.) very freq. 



810. P. multiflorus Willd. (Herm. Miiller, 'Fertilisation,' p. 217; Kirchner 

 ' Flora v. Stuttgart,' pp. 575-6 ; Knuth, ' Bloemenbiol. Bijdragen.') The flowe 

 mechanism of this species agrees completely with that of P. vulgaris, and was firs 

 described by Farrer (Ann. Mag. Nat. Hist., London, Ser. 4, ii, 1868, pp. 256-60). 



According to Ogle (Pop. Sci. Rev., London, ix. 1S70. p. 166), the flowe 

 infertile when bees are excluded, but Kirchner says that they can produce perfec 

 fruits by self-fertilization. The honey-bee and other small bees which are too feebl* 

 to depress the carina, use the holes made by Bombus terrester Z. in the calyx fo 

 stealing nectar. Hermann Miiller states that more powerful bees, with a sufficient! 

 long proboscis, alight upon the left ala and first touch the stigma with the base 

 their proboscis, when they thrust it into the base of the flower, and thus effect cross 

 pollination as in P. vulgaris. As the interlocked alae and carina are pressed down 

 wards, the spirally twisted end of the style protrudes from the tip of the carina, whicl 

 is also coiled into a spiral of two turns. The stigma faces downwards and to the left 

 while the pollen-covered stylar brush rubs against the base of the bee's proboscis 

 and dusts it afresh. When insects visit the flowers cross-pollination is therefor 

 assured, and self-pollination prevented. Hermann Miiller states that automati 

 self-pollination is impossible, as the stigma projects from the tip of the carina, whil 

 the pollen is enclosed within it 



Visitors. I several times observed (at Kiel) Bombus hortorum Z. $ as a 

 invited guest. Schletterer records Eucera longicornis Z. for the Tyrol. 



