308 LAMARCK, HIS LIFE AND WORK 
during a limited time and with the aid of the con- 
traction of several of his muscles. 
‘‘TIf the vertebral column of the human body 
should form the axis of this body, and sustain the 
head in equilibrium, as also the other parts, the man 
standing would be ina state of rest. But who does 
not know that this is not so; that the head is not 
articulated at its centre of gravity; that the chest 
and stomach, as also the viscera which these cavities 
contain, weigh heavily almost entirely on the an- 
terior part of the vertebral column; that the latter 
rests on an oblique base, etc.? Also, as M. Richerand 
observes, there is needed in standing a force active 
and watching without ceasing to prevent the body 
from falling over, the weight and disposition of parts 
tending to make the body fall forward. 
‘“ After having developed the considerations re- 
carding the standing posture of man, the same 
savant then expresses himself: ‘ The relative weight 
of the head, of the thoracic and abdominal viscera, 
tends therefore to throw it in front of the line, 
according to which all the parts of the body bear 
down on the ground sustaining it; a line which 
should be exactly perpendicular to this ground in 
order that the standing position may be perfect. The 
following fact supports this assertion: I have ob- 
served that infants with a large head, the stomach 
protruding and the viscera loaded with fat, accustom 
themselves with difficulty to stand up straight, and 
it is not until the end of their second year that they 
dare to surrender themselves to their proper forces; 
they stand subject to frequent falls and have a nat- 
ural tendency to revert to the quadrupedal state.’ 
(Phystologie, vol. ii., p. 268.) 
‘* This disposition of the parts which cause the 
erect position of man, being a state of activity, and 
consequently fatiguing, instead of being a state of 
rest, would then betray in him an origin analogous 
