8o DESIGN IN NATURE 



PLATE XLIX {continued) 



Fig. 7. — Skeleton and outline of man (Homo sapiens). Shows longitudinal and transverse cleavage in arms and legs ; radiating 

 cleavage in the hands and feet ; and transverse cleavage in the vertebral column and ribs, a, Shoulder joint (universal) ; b, elbow 

 joint (spiral and hinge) ; c, wrist joint (universal in a way) ; d, hand joints (spiral and hinge ); a, b, humerus ; b, c, radius and ulna 

 plaited and showing spirality ; c, d, bones of wrist and hand ; e, hip joint (universal) ; f, knee joint (spiral and hinge); g, ankle 

 joint (universal in a way); h, foot joints (spiral and hinge); e, f, femur; /, g, tibia and fibula; g, /i, bones of foot. The spiral 

 configuration of the bones forming the human skeleton is given at Plate xix., Figs. 3 and 4 ; Plate xx., Figs. 2 and 4 ; and Plate xxi., 

 Figs. 1 and 2. The spiral configuration of the bones of the elephant is seen in Plate xx., Fig. 3. 



Fig. 8. — Dissection and drawing by the Author of the wings of the pheasant (Pliasianus colchicus). Shows extreme cleavage and 

 radiation and large superficial area of the wings. Compare with Figs. 1 and 2 of this Plate. The right wing is extended, and shows 

 the muscles of the slioulder, the muscles and elastic structures of the wing, and the arrangement of the primary and secondary feathers 

 in the wing. The left wing is flexed, and displays the skin and elastic structures which assist in folding the wing as corrugated and 

 puckered. For details of the anatomy of the wing see further on. 



PLATE L 



Plate 1. illustrates longitudinal cleavage and radiation in the travelKng organs of animals (caudal and 

 other fins, flippers, feet, wings, &c.), and ho-w intimately these fundamental cleavage arrangements are associated 

 with locomotion in all its forms. 



Fig. 1. — Shows a series of original drawings made for the Author by C. Berjeau in 1867 (vide Trans. Linn. Soc. vol. xxvi.). These 

 drawings, taken from nature, reveal the important fact that the travelling organs of animals increase in size according as the medium 

 traversed becomes more and more tenuous and affords less and less support. Thus the feet of the deer, adapted for land transit, are 

 smaller than the feet of the bird, otter, frog, platypus, seal, and turtle adapted for swinmiing ; these, again, being smaller than the 

 pseudo-wings of the flying fish, flying lizard, and flying lemur ; the latter being, in turn, smaller than the wings of insects, birds, and 

 taats adapted for flight. The subjects are arranged with a view to comparison and to facilitate reference. 



A. Small foot of deer adapted to land transit. 



B. Webbed foot of otter slightly expanded. Adapted for land and water transit. 



C. Webbed foot of frog, considerably expanded. Adapted for land and water ; chiefly water. 



D. Webbed foot of platypus (duck mole), greatly expanded. Adapted chiefly for water. 

 K. Webbed hind foot of seal, greatly expanded. Adapted mainly for water. 



F. Wings of swallow, enormously expanded. Adapted solely for aerial transit. Compare with foot of deer (A), adapted solely 

 for land transit. 



G. Flippers of turtle, greatly expanded. Adapted almost exclusively for water, a, b, Anterior thick margin; c, posterior thin 

 margin of fore flipper ; d, e, posterior thin margin of hind flipper. 



H. Tail and caudal fin of fish, largely expanded. Adapted wholly for water transit. The fish moves its tail laterally and with a 

 spiral fignre-of-8 movement ; the vibration occurring on either side of the mesial plane (a). 



I. Tail and caudal fin of manatee (sea cow), greatly expanded as in fish. Adapted wholly for water transit. The tail moves 

 vertically on either side of the mesial line (a), and makes a figure-of-8 track on the water, as happens in the fish. 



J. Portion of body and swimming wing and foot of penguin. The swimming wing is much smaller and stiffer than the flying 

 wing. It twists and uiitwists in action and forms a beautiful screw (a, b, c). The swimming foot (d) is webbed, and larger than the 

 un webbed terrestrial bird's foot. 



K. Flying-fish with greatly enlarged pectoral fin, which forms a pseudo-wing. It makes short flights, and connects the travelling 

 organs adapted for the water and the air. 



L. Flying lizard with flying membrane (pseudo-wings) supported by its ribs. It glides from heights over considerable distances. 



M. The bat with its wings fully extended : tlie increase in the size of the travelling orgnns (wings) is excessive. Compare with 

 the foot of the deer (A), the tail of the fish (H), the flipper of the turtle (G), and the flipper of the seal (E). The bat is adapted 

 exclusively for aerial transit. 



N. Flying lemur with flying membrane supported by body, extremities and tail. The flying lizard (L) and flying lemur (N) 

 connect the travelling organs adapted i'or the land and air. The increase in the extent of the surfaces engaged in transit is very con- 

 siderable. 



Fig 2.— The tail of the herring {Glwpea harengus), drawn by C. Berjeau for the Author, in the closed, semi-closed, and fully 

 e.xpanded condition. Shows longitudinal cleavage and radiation. The tail is the chief swimming organ, and no better example can be 

 given of the utility of cleavage and radiation for the purposes of progression. The tail divaricates when making the figure-of-8 move- 

 ments in swimming, and so alternately seizes and lets go the water on which the progress of the fish depends. The tail is a finely- 

 graduated, flexible, elastic structure. 



Fig. 3. — The tail of the mackerel {Scomber scomber), drawn by C. Berjeau for the Author, in the closed and expanded condition 

 Displays the same characteristics as the tail of the herring (Fig. 2). 



Fig. 4. — The heterocercal tail of a shark with the caudal portion of the vertebral column terminating in the upper or major lobe 

 Shows longitudinal and radiating cleavage. The (jrgan, as in the fish, is finely graduated, flexible, and elastic. It tapers from "the root 

 in every direction. Drawn by C. Berjeau from a specimen in the museum of the Author, 



