76 



ANIMAL MECHANICS 



to be as 245 to 160; or the lesser was 65 per cent, of the 

 greater. 



Two equal lengths of the dried tendons were then weighed, 

 and found to be in the proportion of 845 to 495, which was 

 assumed to be the proportion of their cross sections. The 

 lesser of these numbers is 59 per cent, of the greater; a re- 

 sult that seems to be as near to the former result derived 

 from the muscles as can be expected in this class of experi- 

 ments. 



A. Comparative Anatomy of the Tendons of the Foot. 

 The flexor muscles of the toes which we have to compare 

 are three in number, viz. : 



Flexor hallucis longus. 

 Flexor digitorum longus. 

 Flexori longo accessories. 



This latter muscle, when it exists, always acts as a guy 

 or force directing the line of force of the long flexor of the 

 toes; but in many animals it is absent, if the tendon of the 

 long flexor does not require to be assisted to keep in the 

 proper direction. The accessory muscle seems also to serve 

 as an addition to the force of the Flexor hallucis, whenever 

 the tendon of this muscle unites with that of the long flexor 

 of the toes ; for the fibres of the accessory are parallel to the 

 tendon of the Flexor hallucis, and pass into it, uniting it with 

 the tendon of the Flexor longus by means of broad slender 

 sheets of fibres. I have found the following arrangement of 

 tendons in various animals : — 



(a.) Man. — In the human foot, the Flexor hallucis, gene- 

 rally, has a tendon that divides into two branches, the largest 

 of which forms the flexor tendon of the great toe, while the 

 smaller branch proceeds to form a portion of the flexor tendon 

 of the second toe. The long flexor of the toes has a tendon 

 branching into four parts, and crosses the flexor tendon of 



