AND PHYSIOLOGY. 



81 



178. Use of the Tarsus .—In the Tarsus we see the value 

 of several bones instead of one. It is the movement of these 

 upon one another that imparts elasticity to the step and firm- 

 ness of support to the whole body ; and hence it is that all 

 artificial legs, produce a limping motion in the body. By no 

 mechanical contrivance can the suppleness of the tarsus and 

 of the muscular actions be supplied. 



179. Two Bones in the Great Toe, and three Bones 

 in all the Ot hers . — The great toe of the foot, like the thumb 

 of the hand, has only two phalanges. This is mainly for the 

 purpose of securing greater strength to the foot in walking 

 and standing. It is also of service for opposition to the other 

 toes, as is seen in those rare cases of persons deprived of their 

 upper extremities, who can readily make use of the foot for 

 many of the delicate purposes to which the hand is adapted, 

 such as writing, using scissors, and placing the crystal in a 

 watch. The remaining toes, like four of the fingers, receive 

 a tendon only at the base of the second and third phalanx, 

 the first one being interposed merely to give strength and 

 slenderness to the extremities, as well as the power of sur- 

 rounding objects in the act of prehension. The slenderness 

 of the fingers above the toes is a distinguishing characteristic 

 of man, showing that the office of the foot is merely to sup- 

 port the body on the ground, and of the hand to perform the 

 business of every-day life in it3 ten thousand forms. 



HYGIENIC INFERENCES. 



180. — 1. Reason of Distorted Banes. — In the early life 

 of man and other vertebrate animals, the animal portion of 

 bones greatly predominates over the earthy constituents, and 

 hence they yield more readily to pressure, but are not so 



178. How do the hones of the Tarsus give elasticity to the step? 179. How do the 

 phalanges of the foot compare with those of the hand in number ? Why are the bones of 

 the hand longer than those of the foot ? ISO. What kind of matter predominates in tha 

 early life of bones ? 



