THE WELCOMES OF THE FLOWERS 143 



mas, having now been fertilized, have withered, at 

 the same time exuding a fresh supply of nectar, 

 which again attracts the flies, whereupon, as 

 shown at D, the anthers open and discharge 

 their pollen upon the insects. In the fourth 

 stage (E), all the functions of the flower having 

 now been fulfilled, the fringe of hairs withers, and 

 the imprisoned pollen-laden flies are permitted to 

 escape to another flower, where the beautiful 

 scheme is again enacted. 



In a paper of this kind it is of course possible 

 only to hint at a few representative examples of 

 floral mechanisms, but these would be indeed in- 

 complete without a closing reference to that won- 

 derful tribe of flowers with which the theory of 

 cross -fertilization will ever be memorably asso- 

 ciated. I have previously alluded to the absolute 

 dependence of the red clover upon the bumble- 

 bee. This instance may be considered somewhat 

 exceptional, though numerous parallel cases are 

 known. Among ordinary flowers this interven- 

 tion of the insect is largely a preferable intention, 

 and though almost invariably fulfilled, a large pro- 

 portion of flowers still retain, as a dernier ressori, 

 the power of at least partial self-fertilization and 

 perpetuity in the absence or neglect of their in- 

 sect cpunterpart, 



