280 



INDEX. 



Electricity,' animal, 49 



— disappearance when te- 



tanized, 50 



— Dii Bois Reymond on, 



50 



— mechanical work substi- 



tuted for, 51 

 D'Esterno on flight of birds, 221 



F. 



Fibre, striped and unstriped, 28' 



— and tendon, 69 



— in old age replaced by tendon, 



98 



Force, what, 5 



— ^ all can be reduced to motion, 8 



— indestructible, 6, 13 



— potential, 12, 14 

 Flight, see Wing. 



— of buzzard, 261 



— of birds, 209 



— of pigeon, 255 



— mechanism of, imitated, 277 



— sailing, of birds, 221 



— slight waste of substance in, 



213 



Frog, signals, 32 



' * Function makes the organ," Guerin, 

 84 



G. 



Gorilia, skull in old and young, 90 

 Guerin on club foot, 97 



— on change of bones through 



age, 90 



— theory of function, 84 



H. 



Hartings on ratio of birds' wings to 



weight, 223, 224 

 Heat, animal, 19 



— loss of, in external organs, 22 



— mechanical equivalent of, 15 



— unit of, 13 



Helniholtz on contraction of muscles, 

 46 



Helmholtz on lost time in muscular 



action, 48 

 Herdenheim's experiments on heat 



and work, 17 

 Hirn on heat and work, 18 

 Homology of muscles, 73 

 Horse not projected into air, 156 



— paces of, 139 



— power, 68 



— transition of paces of, 172 



— various authors on, 145 



— Yincent and Goiffon on, 151 



— zootrope figures of, 177 

 Hovering of birds, 221 

 Humerus, curvatures in head of, 92 



— a contorted femur, 91 



I. 



India-rubber, change of heat into 

 work in, 39 



J. 



Joule on equivalence of force, 15 



K. 



Kaleidophone rod, tracing of, 191 

 — — with wing ot 

 wasp, 193 

 Kangaroo, development of crural 

 muscles in, 71 



L. 



Lamarck's development theory, 77 

 Latour on movement of bird's wing, 

 212 



Lavoisier's theory of animal heat, 20 

 Levers in animal skeleton, 65 

 Liais on double action of bird's 



wing, 273 

 Life, organic acts of, 28 



— of relation, 28 

 Locomotion, aerial, 180-277 



— aquatic, 106 



— terrestrial. 102 



