
CONSERVATION OF ENERGY IN LIVING ORGANISM. 103 
THE CONSERVATION OF ENERGY IN THE LIVING 
ORGANISM. 
BY W. O.‘ ATWATER. 
_ In its material manifestations life consists of transformations 
of matterand energy. The plaut gathers the elements it needs 
from soil and air, and builds them into its own substance. It 
does so ‘‘ by grace and bounty of the sun,’’ whose energy en- 
_ ables the plant to do the building and is stored in the substance 
of the plant. The ox eats the grass and transforms it into 
flesh, which makes our meat; we gather wheat and make 
bread; and when we eat the bread and meat their substance is 
transformed into the material of our bodies, or is utilized for 
the production of heat and muscular energy; thus the energy 
which comes from the sun becomes our energy for bodily 
warmth and work. 










b- : Experimental research has shown several ways in which the 
ingredients of ordinary food and body material serve as fuel. 
They are oxidized in the body; in the oxidation, their poten- 
tial energy becomes kinetic and is thus made useful to the 
body; part of this kinetic energy appears as heat; another 
‘part appears as muscular work; in yielding energy by its own 
oxidation, food protects the material of the body and of other 
food from consumption. 
_ Nutrition thus consists largely in transformations of food 
food and body material into energy. When matter is trans- 
both food and body material in nutrition are regulated largely 
by the needs of the body for energy. To learn the laws of 
nutrition we must know how these transformations take place; 
the study of them is the object of the experiments with the 
respiration calorimeter. | 
. 7) 
= ant i 
into body material and the ultimate transformations of both . 
formed energy is transformed also, and the transformations of — 

