Not Found

The requested URL /mbrowse/msdb/OriginOfSpecies/description/is/It+may+be+worth+while+to+give+another+and+more+complex+illustration+of+the+action+of+natural+selection. Certain+plants+excrete+sweet+juice,+apparently+for+the+sake+of+eliminating+something+injurious+from+the+sap:+this+is+effected,+for+instance,+by+glands+at+the+base+of+the+stipules+in+some+[[Leguminosae|Leguminosae]]+and+at+the+backs+of+the+leaves+of+the+common+laurel. [[[[[images/sap.jpg|sap]]]]] [[[[[images/Leguminosae.jpg|Leguminosae]]]]] [[[[[images/Laurel+Wreath.jpg|Laurel+Wreath]]]]] This+juice,+though+small+in+quantity,+is+greedily+sought+by+insects;+but+their+visits+do+not+in+any+way+benefit+the+plant. Now,+let+us+suppose+that+the+juice+or+nectar+was+excreted+from+the+inside+of+the+flowers+of+a+certain+number+of+plants+of+any+species.+Insects+in+seeking+the+nectar+would+get+dusted+with+pollen,+and+would+often+transport+it+from+one+flower+to+another. [[[[[images/insect.jpg|insect]]]]] [[[[[images/nectar.jpg|nectar]]]]] [[[[[images/pollen.jpg|pollen]]]]] The+flowers+of+two+distinct+individuals+of+the+same+species+would+thus+get+crossed;+and+the+act+of+crossing,+as+can+be+fully+proved,+gives+rise+to+vigorous+seedlings+which+consequently+would+have+the+best+chance+of+flourishing+and+surviving. The+plants+which+produced+flowers+with+the+largest+glands+or+nectaries,+excreting+most+nectar,+would+oftenest+be+visited+by+insects,+and+would+oftenest+be+crossed;+and+so+in+the+long+run+would+gain+the+upper+hand+and+form+a+local+variety. The+flowers,+also,+which+had+their+stamens+and+pistils+placed,+in+relation+to+the+size+and+habits+of+the+particular+insects+which+visited+them,+so+as+to+favour+in+any+degree+the+transportal+of+the+pollen,+would+likewise+be+favoured. [[[[[images/stamen.jpg|stamen]]]]] [[[[[images/pistil.jpg|pistil]]]]] We+might+have+taken+the+case+of+insects+visiting+flowers+for+the+sake+of+collecting+pollen+instead+of+nectar;+and+as+pollen+is+formed+for+the+sole+purpose+of+fertilisation,+its+destruction+appears+to+be+a+simple+loss+to+the+plant;+yet+if+a+little+pollen+were+carried,+at+first+occasionally+and+then+habitually,+by+the+pollen-devouring+insects+from+flower+to+flower,+and+a+cross+thus+effected,+although+nine-tenths+of+the+pollen+were+destroyed+it+might+still+be+a+great+gain+to+the+plant+to+be+thus+robbed;+and+the+individuals+which+produced+more+and+more+pollen,+and+had+larger+anthers,+would+be+selected./ was not found on this server.