1 54 Difficulties of the Theory Chap. vi. 



constructed is the feathered wing of a bird and the membrane- 

 covered wing of a bat ; and still more so the four wings of a butter- 

 fly, the two wings of a fly, and the two wings with the elytra of a 

 beetle. Bivalve shells are made to open and shut, but on what a 

 number of patterns is the hinge constructed,— 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 nutritious, 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 hermaphrodites, 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 inexhaustible 

 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 recep- 

 tacles, with the stamens and pistils modified in many ways, some- 

 times forming trap-like contrivances, and sometimes capable of 

 neatly adapted movements through irritability or elasticity. I rom 

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

 extraordinary adaptation as that lately described by Dr. Criiger in 

 the Coryanthes. This orchid has part of its labellum or lower lip 

 hollowed out into a great bucket, into which drops of almost pure 

 water continually fall from two secreting horns which stand above 

 it ; and when the bucket is half full, the water overflows by a 

 spout on one side. The basal part of the labellum stands over the 

 bucket, and is itself hollowed out into a sort of chamber with two 



