110 



PHYSIOLOGY 



CHAP. 



In order to increase the base of support and to obtain more 

 stable equilibrium it is only necessary to set the feet further apart 

 upon the ground. This is often done where the erect posture has 

 to be long maintained. 



From these forms of symmetrical vertical posture we must dis- 

 tinguish the asymmetrical vertical posture, in which almost the 

 whole weight of the body falls upon one leg, the other being 

 slightly flexed and placed in advance. In this posture (Jianchee~) 

 the line of gravity falls through the extended limb which supports 



FIG. 71. Displacement of centre of gravity in postures a, b, c. (Braune and Fischer.) 

 Centres of gravity shown as black dots on the vertical lines. 



the body, and the trunk consequently inclines towards this side. 

 The different forms of this posture, which is very natural and 

 instinctive, are determined by the angle formed by the longi- 

 tudinal axes of the two limbs or by the distance between the 

 two soles of the feet. 



IV. We should next consider briefly the mechanism of 

 equilibration in the different postures of the human body, but 

 must here confine ourselves to the horizontal posture, the sitting 

 posture, and the common erect attitudes. 



The horizontal posture is the easiest to maintain because 

 it unites as completely as possible the two conditions of stable 

 equilibrium, i.e. an extensive base of support, and the maximum 

 approximation of the centre of gravity to it. As muscular con- 



