<)2 



ANIMAL MECHANICS. 



On examining Tables XV. and XIX., and the result just 

 stated for the long flexor of the foot of the kangaroo, it appears 

 that the friction of the tendons and muscles, and the surplusage 

 of strength provided against any sudden accident, may con- 

 sume as much as 75 or 80 per cent, of the strength of the ten- 

 don, leaving only one-quarter or one-fifth of that tendon to be 

 strained by the contraction of the muscular fibres. This, how- 

 ever, can only occur in very extreme cases, and the force ex- 

 pended in such cases reappears as heat, and so assists the 

 general purposes of the body, which requires its temperature to 

 be maintained at ioo° F. in order to perform its functions. In 

 the great majority of cases the muscles, in performing their 

 usual duties, act in such a position of the tendons as to cause 

 the minimum amount of friction, and to produce the maximum 

 of external effect ; the surplus strength of the tendons being 

 provided as a safeguard against strains that rarely occur, and 

 then only as accidents. 



(b). Chimpanzee. — In this animal the flexor hallucis sup- 

 plies the whole tendons of the first and fourth toes, and part 

 of the tendons of the second and third toes; while the flexor 

 digitorum supplies the remaining parts of the tendons of the 

 second and third toes, and the whole tendon of the fifth toe. 

 This arrangement would seem to indicate a concurrence in 

 action between the first and fourth toes, which must corre- 

 spond to some peculiarity in the animal's mode of grasping 

 objects; while the fifth or outer toe retains its indepen- 

 dence. 



(c.) Monkeys of the Old Continent. —The Macaques of Asia, 

 and the long-tailed Monkeys of Africa, such as the Mangabeys, 

 are characterized by an arrangement of flexor tendons of the 

 foot, which is shown in Fig. 7, representing the flexor tendons 

 of the foot of the Bruh, or Pig-tailed Macaque (Macacus Ne- 

 mestrinus), seen from below, and drawn aside from their natural 

 positions, so as to exhibit their mechanical arrangement. 



