RESPIRATION 7 



Hence apart from seasonal variations the daily nervous activities 

 are pretty constant in total amount. 



Although the internal body temperature is actually very con- 

 stant, yet a very moderate actual rise or actual fall in body 

 temperature is sufficient to increase or diminish oxidation very 

 materially. In fever, for instance, the oxidation in the body is 

 greater than it would be without the rise of temperature but with 

 other conditions the same. The oxidation in fever is, however, 

 only a fraction of that during even very moderate exertion. 



When we examine still more closely, and in the light of the facts 

 which are continuously becoming revealed by pathology and 

 pharmacology, we begin to realize that "energy requirements" 

 depend on an infinite multitude of associated "normal conditions." 

 An upset in the proportion of, say, calcium or potassium in the 

 blood, or in that of substances produced in minute amounts in 

 one or other of the "ductless glands" or supplied to the body 

 along with the other main constituents in ordinary food, will 

 dramatically end "energy requirements" by that mysterious phe- 

 nomenon which we call death* and which we are so familiar with 

 that we almost cease to speculate about its nature. 



At first sight death may seem to become intelligible when we 

 find that in the higher animals its immediate cause is want of 

 oxygen in the tissues owing to interruption of the circulation or 

 breathing. But further examination shows us that death is no mere 

 stoppage of an engine owing to lack of air or fuel, but also total 

 ruin of what we took to be machinery. It is a mysterious dissolu- 

 tion in the association together of the infinitely complex group of 

 normals which constitute the life the <wrcs of an organism ; 

 and an examination of the fragments left has thrown no light on 

 why the association should have existed at all, or endured so long. 

 The outward form and internal arrangenent and composition of 

 the dead body tell their story of life to him who can interpret their 

 hieroglyphics ; but there is no life visible. The gulf between the 

 dead and the living is a gulf across which our present intellectual 

 vision does not reach, and we only deceive ourselves when we 

 sometimes imagine that it does. Thus when we ask what determines 

 those "energy requirements" which determine consumption of 

 oxygen and output of carbon dioxide in the living body, the only 

 answer we can at present elicit from experimental investigation 

 is that the energy requirements are one side of the <wris of the 

 organism. To those who object that the <f>v<ris is a mere name, 

 and that physiology must be simply physics and chemistry I can 



