172 DIFFICULTIES OF THE THEORY 



remotely allied, by organs in appearance, though not in 

 development, closely similar. On the other hand, it is a 

 common rule throughout nature that the same end should 

 be gained, even sometimes in the case of closely related 

 beings, by the most diversified means. How differently con- 

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

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

 a butterfly, 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 con- 

 structed, 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 baloon-like envelope, by being 

 embedded in pulp or flesh, formed of the most diverse parts, 

 and rendered nutritious, as well as conspicuously colored, 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 fertiliza- 

 tion. 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, $#4 sometimes capable of RffttSly 34aptec| 



