THE BREATH OF LIFE 



In warm climates the fur of animals and the wool 

 of sheep become thin and light. The colder the 

 climate, the thicker these coverings. Such facts 

 only show that in the matter of adaptation among 

 living organisms, there is a factor at work other 

 than chemistry and physics — not independent of 

 them, but making a purposive use of them. Cut 

 off the central shoot that leads the young spruce 

 tree upwards, and one of the shoots from the whirl 

 of lateral branches below it slowly rises up and 

 takes the place of the lost leader. Here is an action 

 not prompted by the environment, but by the mor- 

 phological needs of the tree, and it illustrates how 

 different is its unity from the unity of a mere ma- 

 chine. I am only aiming to point out that in all 

 living things the material forces behave in a pur- 

 posive way to a degree that cannot be affirmed of 

 them in non-living, and that, therefore, they imply 

 intelligence. 



Evidently the cells in the body do not all have 

 the same degree of life, — that is, the same degree 

 of irritability. The bone cells and the hair cells, for 

 instance, can hardly be so much alive — or so irri- 

 table — as the muscle cells; nor these as intensely 

 alive as the nerve and brain cells. Does not a bird 

 possess a higher degree of life than a mollusk, or a 

 turtle? Is not a brook trout more alive than a mud- 

 sucker? You can freeze the latter as stiff as an icicle 

 and resuscitate it, but not the former. There is a 



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