17 



although this Table represents the friction in the hand and foot of 

 various animals, you are to remember that the friction is phis in one 

 case and mimis in the other. The strength of the tendons in the fore- 

 arm always exceeds the strength of the tendons of the fingers ; while 

 the strength of the tendons of the toes exceeds the strength of the 

 tendons of the leg. In the wolf the corresponding figures are 31.4 and 

 34 ; in the bear, 35, and 25.9 ; in our cousin, the negro monkey, 27*4 

 and 8. This animal, you see, fully justifies the title which Cuvier 

 applied to him of quadrumanous, for he has only a friction of 8 per 

 cent, in his foot, because he uses it very much as a hand for the pur- 

 poses of climbing ; this is apparent in the low coefficient of friction 

 shown in the hind foot. 



The animals whose tendons suffers least from friction, at the wrist 

 and ankle, are" the goat and the kangaroo. The wrist of the goat is 

 so admirably constructed that no force whatever is lost. The animal 

 climbs a hill, runs up rocks, jumps from point to point, and he does so 

 mainly by this admirable arrangement by which no force whatever is 

 lost by friction in the wrist The hind foot of the kangaroo, which is 

 the great organ of locomotion in this animal, presents no friction at the 

 heel. The most perfect organ of locomotion that we are acquainted 

 with amongst quadrupeds (if we may call the kangaroo a quadruped, 

 for he only uses two feet in locomotion) is the hind leg of the boomer 

 kangaroo. The investigation which I have carried out in between 

 seventy and eighty distinct animals shows in a most conclusive manner 

 that the law of least action is attended to in this department of nature 

 down to the most minute details. Even the expense of producing a few 

 grains more or less of this glue (for a tendon is nothing but common 

 glue) is carefully attended to ; and in the laboratory of Nature the most 

 rigorous and parsimonious economy is observed. Not even one grain 

 of material is ever used when less would suffice for the purpose. 



This may be carried out into very minute details which time will not 

 allow me further to develope. I will merely call your attention to a 

 rough sketch of the hind feet of monkeys of the old and the new world, 

 which present many remarkable differences in construction from the 

 feet of other animals. Their feet, as I said before, are fully entitled to the 

 name of hands. We may classify the old and the new world monkeys 

 by the peculiar arrangement of the tendons of their feet. In both, the 

 tendons of the feet are supplied by two great muscles— the flexor hal- 

 lucis longus and the flexor digitorum longus. (Fig i.) You can see 

 the distribution which I have endeavoured to show here. You see that 

 the muscle of the great toe supplies half the first toe, the whole of the 

 second, and the whole of the fifth ; the other tendon supplies half the 

 first toe, the whole of the third, and the whole of the fourth. There- 

 fore the most natural action for the old world monkey would be to put 



C 



