360 



Rev. S. Haughton on Animal Mechanics. [May 19, 



the fingers, we should expect the strength of the tendon above the wrist 

 to be greater than the united strengths of all the finger- tendons. 



Conversely, in a proper foot, the force is applied by the ground to the 

 extremities of the tendons of the toes, and transmitted to the flexor 

 muscles of the leg, by means of the tendons of the inner ankle, which 

 undergo friction in passing round that and the other joints of the foot. 

 In this case, therefore, we should expect the united strengths of the flexor 

 tendons of the toes to exceed the strength of the flexor tendons above the 

 heel. 



In the case of the hand, friction acts against the muscles ; in the case 

 of the foot, friction aids the muscles. 



I have measured the relative strengths of the deep flexor tendons of the 

 hand above and below the wrist in several animals, and also the relative 

 strengths of the long flexor tendons of the foot above and below the ankle 

 in the following manner : — 



I weighed certain lengths of the tendons above the wrist and ankle, and 

 compared these weights with the weights of equal lengths of the flexor 

 tendons of the fingers or toes, assuming that the weights of equal lengths 

 are proportional to their cross sections, and these again proportional to 

 the strengths of the tendons at the place of section. The difference be- 

 tween the weights above and below the joint represents the sum of all the 

 frictions experienced by the teudons between the two points of section. 



The following Tables contain the results of my measurements : — 



Table I. Friction of Long Flexor Tendons of Toes. (Cross section of 

 toe tendons greater than cross section of muscle tendons.) 



Amount of 

 friction, 

 per cent. 



1. Pyrenean Mastiff .... 65*4 



2. African Lion 59 '0 



3. Common Fox 57*6 



4. African Jabiru 56*8 



5. American Rhea 52-4 



6. Indian Jackall 49*2 



7. American Jaguar .... 49'2 



8. New- Zealand Weka Rail 47*5 



9. Silver Pheasant 47*4 



10. Bengal Tiger 46*0 



11. Indian Leopard 45-5 



12. Six-banded Armadillo . . 44*4 



13. Three-toed Sloth 42 5 



14. Black Swan 36'0 



15. Common Hare 36' 0 



16. European Wolf 34 0 



Amount of 

 friction, 

 per cent. 



17. Australian Dinjo. ..... 33*8 



18. Japanese Bear 31*7 



19. Virginian Bear 25 ■ 9 



20. Common Llama 25*9 



21. Hedgehog 25*0 



22. African Ostrich 24 -6 



23. Common Otter 19*8 



24. Man (mean of 5) .... 16'2 



25. Spider-Monkey 12'3 



26. Goat 9*5 



27. One-horned Rhinoceros 9'0 



28. Negro-Monkey 8-0 



29. Brahmin Cow 6 8 



30. Nemestrine Macaque . . 2*0 



31. Boomer Kangaroo .... O'O 



