126 Flowers and their Unbidden Guests. 



This kind of visit, however, in which a hole is gnawec 

 and the nectar sucked out laterally, would of course b( 

 a most unwelcome one to the flower, which would los( 

 all the advantages of cross-fertilisation, as a reward fo: 

 which it offered its nectar. But let the calyx be in 

 flated merely to such a degree that its wall shall lie a 

 a greater distance from the nectary than can b( 

 traversed by the proboscis of a humble-bee, and al 

 danger of this injurious mode of access will be avoided 

 and the bee compelled to avail itself of the natura 

 entrance, at the margins of which are placed the anthers 

 and the stigmas.^ 



The same result as is obtained in the foregoing 

 instance by the inflation of the calyx into a bladder-likt 

 form can also be arrived at in another way, namely, bj 

 the calyx, or the bracts that surround the flower, hein^ 

 formed of very tough tissue — so tough that it can witl 

 difficulty be gnawed into a hole even by a strong humble- 

 bee. This, in the majority of cases, is the only interpre- 

 tation to be found for those stiff hard calyxes and bracts 

 which are usually made of dry membranous tissue, bul 

 are sometimes so thickened as almost to resemble 



^ [This use of an enlarged calyx as presenting an additional im- 

 pediment to lateral gnawing was, to the best of my belief, first 

 suggested by myself [Poip. 8c. Review, 1870, pp. 47 and 168). 

 According, however, to H. Miiller, the flower which I instanced, 

 viz., Pedicularis, is not one to which this explanation applies. A 

 further use to which an inflated calyx is at times subservient has 

 been pointed out by F. Hildebrand (Verbreit. der Pflauzen. s. 64) 

 It aids in the dispersal of the seeds. — Editor.] 



