THE DAILY LOSSES OF THE BODY. 



The living Body thus loses daily in round numbers 4 

 kilograms of matter (9_Jbs.) and, since it is unable to 

 create new matter, this loss must be compensated for from 

 the exterior or the tissues would soon dwindle away alto- 

 gether; or at least until they were so impaired that life 

 came to an end. After death the losses would be of a differ- 

 ent kind, and their quantity much more dependent upon 

 surrounding conditions; but except under yery unusual 

 circumstances the wasting away would still continue in the 

 dead Body. Finally, the composition of the daily wastes 

 of the living Body is tolerably constant; it does not simply 

 lose a quantity of matter weighing so much, but a certain 

 amount of definite kinds of matter, carbon, nitrogen, oxygen, 

 and so on; and these same substances must be restored to 

 it from outside, in order that life may be continued. To 

 give a stone to one asking for bread might enable him, if 

 he swallowed it, to make up the weight of matter lost in 

 twenty-four hours; but bread would be needed to keep 

 him alive. The Body not only requires a supply of matter 

 from outside, but a supply of certain definite kinds of 

 matter. 



The Losses of the Body in Energy. The daily expendi- 

 ture of matter by the living Body is not the only one: as 

 continuously it loses in some form or another energy, or 

 the power of doing work; often as mechanical work ex- 

 pended in moving external objects, but even when at resti 

 energy is constantly being lost to the Body in the form of | 

 heat, by radmtion and conduction to surrounding objects, 

 by the evaporation of water from the lungs and skin, and 

 by removal in warm excretions. Unless the Body can 

 make energy it must therefore receive a certain supply of 

 it also from the exterior, or it would very soon cease to- 

 carry on any of its vital work ; it would be unable to 

 move and would cool down to the temperature of surround- 

 ing objects. The discoveries of this century having shown 

 that energy is as indestructible and uncreatable (see Phy- 

 sics) as matter, we are led to look for the sources of the 

 supply of it to the Body; and finding that the living Body 

 daily receives it and dies when the supply is cut off, we no 



