DIFFICULTIES OF THE THEORY 203 



from the long row of neatly interlocking teeth in a Nucula 

 to the simple ligament of a Mussel ! Seeds are disseminated 

 by their minuteness, — by their capsule being converted into a 

 light balloon-like envelope, — by being embedded in pulp or 

 flesh, formed of the most diverse parts, and rendered nutri- 

 tious, as well as conspicuously coloured, so as to attract and 

 be devoured by birds, — by having hooks and grapnels of 

 many kinds and serrated awns, so as to adhere to the fur of 

 quadrupeds, — and by being furnished with wings and plumes, 

 as different in shape as they are elegant in structure, so as to 

 be wafted by every breeze. I will give one other instance ; 

 for this subject of the same end being gained by the most 

 diversified means well deserves attention. Some authors 

 maintain that organic beings have been formed in many ways 

 for the sake of mere variety, almost like toys in a shop, but 

 such a view of nature is incredible. With plants having 

 separated sexes, and with those in which, though hermaphro- 

 dites, the pollen does not spontaneously fall on the stigma, 

 some aid is necessary for their fertilisation. With several 

 kinds this is effected by the pollen-grains, which are light 

 and incoherent, being blown by the wind through mere chance 

 on to the stigma ; and this is the simplest plan which can 

 well be conceived. An almost equally simple, though very 

 different, plan occurs in many plants in which a symmetrical 

 flower secretes a few drops of nectar, and is consequently 

 visited by insects ; and these carry the pollen from the anthers 

 to the stigma. 



From this simple stage we may pass through an inex- 

 haustible number of contrivances, all for the same purpose 

 and effected in essentially the same manner, but entailing 

 changes in every part of the flower. The nectar may be 

 stored in variously shaped receptacles, with the stamens and 

 pistils modified in many ways, sometimes forming trap-like 

 contrivances, and sometimes capable of neatly adapted move- 

 ments through irritability or elasticity. From such structures 

 we may advance till we come to such a case of extraordinary 

 adaptions as that lately described by Dr. Criigcr in the 

 Coryanthes. This orchid has part of its labcllum or lower 

 lip hollowed out into a great bucket, into which drops of 

 almost pure water continually fall from two secreting horns 



