214 



DESIGN IN NATURE 



Fig. 39.— Shows ventral aspect of the hard and soft jjarts— muscles, tendons, elastic 

 tissues, ligaments, and bones— of the wing of the snipe (GalUnago m/eslis). In the 

 figure the left wing is flexed and the right wing fully extended. The parts marked 

 c, g, h, i (especially A, i) show where the wing is flattened out, soliditted, and strengthened 

 to support the roots of the primary and secondary feathers which are the mimediate 

 instniments of flight. The primary and secondary feathers are seen in position at 

 Fio'. 40. a, b, Muscles connected with the elastic stractures of the wing ; c, d, c, /, 

 g, \ i, musculo-fibro-elastic tissues which are mainly concerned in flexing the wing. 

 The gi-eat depressor or chest muscles are seen between the wings. (From a dissection 

 and drawing by the Author.) 



The modifications and presence of claws in the wings of the Archseopteryx are less remarkable than the modifi- 

 cations met with in the Pterodactyl. The Pterodactyl, or flying reptile, as it is frequently called, had wings much 



more modified than those of the Archse- 

 opteryx, as shown at Fig. 37. 



Similar remarks are to be made of the 

 wings of the modern bat (Fig. 38). 



Still more remarkable are the modifi- 

 cations of the wings of existing birds, where 

 the bones of the hands are reduced in 

 number ; some being greatly enlarged, and 

 soldered together to provide a flat, osseous 

 support for the roots of the primary and 

 secondary feathers, which play a most im- 

 portant part in all air-flying birds (Fig. 39). 



The points which I wish to estabhsh in 

 the present connection are : — 



1. That the typical five fingers or toes 

 in the limbs of the majority of vertebrates 

 are not permanent, but a vanishing quantity : 

 the toes of the hind Hmbs being, in many 

 cases, fewer than the fingers of the fore 

 limbs. 



2. That the fore hmbs of the elephant 

 and of many fossils have five fingers or 

 dioits : that in some of the Dinosaurs 

 (extinct reptiles) there are fouj digits in the 

 fore hmb and only three in the hind hmb : 

 that in the extinct moa there are three toes 

 with a rudimentary fourth toe to the hind 

 limbs : that in the modern emu there are 

 three toes to each hind hmb : that in the 

 ostrich there are only two toes to each 

 hind hmb : that in the camel, ox, and deer 

 there are two digits to each of the hmbs : 

 that of the two toes of the ostrich, one is 

 very much longer and stronger than the 

 other : that there is also a shght deviation 

 in this direction in the camel : that in the 

 horse there is only one digit to each limb — 

 this being very much enlarged and very 

 strong. 



3. That the modifications in the digits 

 of the fore limbs of vertebrates are very 

 remarkable, and cannot be accounted for as 

 apart from a First Cause and Design : that 

 in some cases not only are the digits 

 suppressed, but other digits are hyper- 

 developed to quite an extraordinary extent : that in the foot of the ostrich, where there are only two digits, the 

 one is dwarfed and the other very greatly enlarged : that in the wing of the pterodactyl there are three digits which 

 are aborted and terminate in hooks — one digit (the fifth) being enormously elongated and hypertrophied : that in 

 the wing of the bird the digits are reduced to three, and that they are run together, solidified, and increased in 

 size to form a fiattened, osseous surface which supports the roots of the primary and secondary feathers, the 

 immediate instruments of flight : that in the horse, only one digit remains for each hmb ; this being phenomenally 

 large and strong. 



4. That there are strong grounds for believing that the variations in the number and shape of the digits of 



Fig. 40. — Shows the dorsal aspect of the hard and soft parts of the wing of the 

 pheasant {Phasianus colchicus). In the right wing the roots of the primary and 

 secondary feathers are exposed to show their relation to the fore arm, hand, and greatly 

 modified phalanges or finger bones. The left wing is fully flexed and ready to make 

 the up stroke. In the left wing the feathers are widely separated, and present a series 

 of vertical knifo-lilce edges through which the air escapes rluring the up stroke ; in the 

 right wing the feathers are spread out and firmly pressed together to jirevent the escape 

 of air during the doMu stroke. (From a dissection and drawing by the Author.) 



