86 DESIGN IN NATURE 



PLATE LIII {continued) 



Small feet suffice for support and propulsion when the surface trod, which supplies the fulcrum for the travelling organs, is vrnyielding. 

 Larger travelling organs are required for the water, which furnishes a yielding fulcrum ; still larger travelling surfaces being required 

 for the air, ^vhere the fulcrum is still more mobile and treacherous (the Author). 



Fig. 2. — Photographs of men walking at a brisk pace, seen from before and behind. Show the double fignre-of-8 curves made by 

 the superior and inferior extremities, and the double twisting movements which occur at the shoulders and hips in walking. The 

 left arm (a) and right leg (h) advance together in curves (see darts) to make one step ; the right arm (c) and left leg (d) advancing 

 together in curves (see darts) to make a second step. The same movements are seen at Fig. 4 of this Plate, where the interrupted line 

 represents the curves made bj' the arms in walking ; the continuous line representing those made by the legs. The twisting movements 

 which occur at the shoulders and hips in walking are seen at h, I, and m, n (see darts) ; those made by the legs and arms at h, i, and j, g. 

 In the central figures the extremities are in the act of reversing (the Author). 



Fig. 3.--The swimming of the sturgeon (Acipeitser sturio), as depicted by the Author in 1867. Shows the double figure-of-8 curves 

 made by the body and tail of the fish as it progresses through the water. The tail makes similar curves, a, h, Line of progress ; 

 c, caudal curve ; d, cephalic curve. The caudal and cephalic curves are complemental and afford fulcra for each other when the 

 effective strokes are made. 



Fig. 4. — Double or figure-of-8 curves made by the arms and legs in walking, as depicted by the Author in 1867. The interrupted 

 line represents the curves made by the arms ; the continuous line the complemental curves made by the legs. The right leg and left 

 arm advance together to make one step ; tlie left leg and right arm advancing together to make a second step. The legs and arms 

 move diagonally, and the curves made liy them cross and produce figtires-of-8. The diagonal movements of the limbs necessitate 

 twisting movements at the hips and shoulders. 



Fig. 5. — Blow-fly with its wings at rest and in motion, as delineated by the Author in 1867. 



A. Blow-fly at rest. 



B. Blow-rty with its body fi.ved and its wings in motion (captive flight). In captive flight the wings twist and untwist as they 

 hurry to and fro and make double or figure-of-8 curves. The tips of the wings describe a figure-of-8 trajectory in space. In free 

 flight the figure-of-8 is opened out to form first a spiral and then a waved track, as shown at Figs. 6 and 9 of this Plate. 



Fig. 6. — Spirid and waved track made by the wings of the insect in free flight. The track in question is indicated by the arrows 

 marked a, b, c, d, e, f, g, h, i, j. k, I, m, n, o, p, q, r, n, t ; the recoil obtained from the air is indicated by the same letters with a dash 

 prefixed (the Author, 1867 aiid 1870). 



Fig. 7.— The flight of the heron (Ardea cinerea), from a photograph by the Aullior. Shows very large wings and small body, as 

 in the bat (Fig 1, C, of this Plate). The wings of the heron and all other birds make figure-of-8, spiral, and waved tracks in flight, as 

 shown at Figs. 6, 9, and 10 of this Plate. 



Fig. 8.— Double spiral curves made by the feet of a bird in swimming, as figured by the Author in 1867. The arrow a, represents 

 the curve made by the right foot during its back or effective stroke ; the arrow h, the curve made at the same time by the left foot 

 during its forward or non-effective stroke. The right and left legs and feet move alternately, and the feet are expanded during the 

 effective strokes and closed during the non-eftective strokes. The swan occasionally moves both feet together. 



Fig. 9 —Spiral and waved track made by the wing of the bird in free flight, as first explained by the Author. The spiral and 

 waved track is indicated by the arrows marked a, 6, r, ,-7, e,/, g, h, i,j, k, I, to, n, o, p, q, r, s, t (the Author, 1867 and 1870). 



Fig. 10.— Waved track made by the wing of the bird in tree flight, as figured by the Author in 1867. a, h. Represent the line of 

 flight. The letters from c to m inclusive, represent the angles made by the wing with the horizon during the down and up strokes. 

 This wing flies forward as a true kite during both the down and up strokes {vide arrows). 



PLATE LIV 



Plate liv. illustrates the double, complemental, figure-of-8 carves made by the extremities of quadrupeds and 

 bipeds in walking ; how similar curves are made by the wing in flying ; and how there are good grounds for boUeving 

 that these curves are fundamental, and first make their appearance in the sinuous movements of spermatozoa, the 

 serpent, and other creeping things. 



Fig. 1.— Trotting horse drawn by the Author to show the double figure-of-8 curves made by the limbs, t, r. Double curves made 

 by the right fore and left hind legs ; u, s, double and complementarv curves made by the left fore and right hind leo-s. The 

 double complementary curves when superposed produce an elongated figure-of-8. The double curves are caused by diagonal 

 movements of the fore and hind limbs of opposite sides, and by twisting movements occurring at the shoulders and hips of the horse. 



Fig. 2.— The serpent as seen crawling, incorrectly and correctly pourtrayed (after Giinther). 



A. The serpent in this figure is wrongly represented as making sinuous vertical movements ; the body being supported at three 

 points only. 



B. The serpent in this figure is rightly represented as making sinuous lata-al movements ; the body beint' more or less in contact 

 with the ground m its entire length. At rr, b, the serpent is gliding forward in double, complemental, figure-of-8 reversing curves • at 

 c, d, It IS stretched out and at rest. In 1867 the Author explained that the travelling organs and extremities in the higher animals 

 whether fins, flippers, wings, or feet, were outgrowths from the trunk and vertebral column, and derived their sinuous fiaure of 8 

 movements therefrom. The following were the words employed at the date in ([uestion : " That the movements of the extremities 

 primarily emanate from the spine is rendered probable by the remarkable powers possessed by serpents. . . . The peculiar endow- 

 ments, therefore, which accompany the possession of extremities, would seem to present themselves in an undeveloped or latent form 

 in the trunk of the reptile." 



Fig. 3.— Photographs of nude female walking, as seen before and behind (after E. Muvbridge). The darts are added by the Author 

 and he is responsible for the description given of this and other photographs by Muybridge employed in the work. The darts show 



