NOTES OX THE IRRITABILITY OF THE STIGMA. 211 



stamens. Soon after the contact (hy which the stigma receives the 

 pollen), the lower lobe folds up, opening' the way for the bee which 

 tlien enters deeper and becomes dusted with a new sii])ply of pollen. 

 That reopening of the lobe takes place in abcnit 10 minutes after 

 the closing seems to be well adapted to the reqnirement of the rase, 

 when we consider the intci-Nal of time which usually elapses before 

 the bee revisits the same ünwer. Tlie nsual deep bhiish purple, or 

 rarer snowy wliite, colour of the corolhi serves no doubt to attract 

 the insects, while tlie hairs on the floor of the lower lip seem to assist 

 the visiting insects in aHgliting. 



In 3Ii)}nihts tirixilciisis, Benrh.. M. sessifolius ]\faxim.. and M. 

 moschatiis, Doug., all of wiiicli I liaNe observed, the mechanism is 

 precisely similar and adapted for the same purpose as Mazus, so 

 that it is hardly necessary to enter into details. 



