70 



as we have seen, do not guide to the nectary. Some do so 

 point, ])ut of these many are in the tube, and of no vahie 

 when the insect has got so far towards his object. Never- 

 theless, while many of the spots, dots, bands, etc., are not 

 guides to the nectary, they serve as signs or advertisements 

 to insects that such flowers are especially nectariferous. 

 Probably there is no flower with these markings but that 

 has nectar somewhere in the blossom. They are always 

 confined to those parts only of the flower which come in 

 contact with insects. It is the contact which causes them. 



Other useful guides are found in the rapid change of 

 colors, Weigelia rosea opens white, and changes to deep 

 rose-purple ; after a time there are but few white flowers 

 and many purple on the shrub. The honey bees visit only 

 the white ones. 



A bumble-bee will fly among a bed of Columbines, per- 

 haps all white ; he goes close to the flowers, looks into this 

 or that, and passes on to others, finally entering some. If 

 the ones he visits are examined, they will all ]>e found to 

 have bright lemon-yellow anthers, while the ones he rejects, 

 though looking just as fresh, are not so, all their anthers 

 have turned to black. Even a change of color in the spots 

 themselves, to which we have previously referred, serves a 

 like purpose, as it indicates that the flower has passed its 

 virgin freshness, and with it its nectar has dried up. 



Real double flowers have no insect visitors, partly double 

 do, and the markings may continue on these for a time by 

 heredity. 



The honey guides on Polygonatum, Solomon's Seal, and 

 Lucoium are green ; on Phlox Drummoudi and Cineraria, 

 white at the centre frequently, while Convolvulus sepium 

 has white, radiating streaks ; they are Indian-red in Tropte- 

 olum ; yellow in tulij), iris, freezia, pontederia, etc ; pur[)le 

 or violet in pansy and white violet, etc. ; cobalt blue in 

 Tulipa Gesneriana ; and violet-black in oriental poppy. 



In Rhododendron, Azalea, Geranium, etc., the special 



