CHAPTER II 



THE WEB OF LIFE 



I. Dependence upon Surroundings 2. Inter-relations of Plants and 

 Animals 3. Relation of Animals to the Earth 4. Nutritive 

 Relations 5. More Complex Interactions 



IN the filmy web of the spider, threads delicate but firm 

 bind part to part, so that the whole system is made one. 

 The quivering fly entangled in a corner betrays itself 

 throughout the web ; often, it is felt rather than seen by the 

 lurking spinner. So in the substantial fabric of the world 

 part is bound to part. In wind and weather, or in the 

 business of our life, we are daily made aware of results 

 whose first conditions are remote, and chains of influence 

 not difficult to demonstrate link man to beast, and flower to 

 insect. The more we know of our surroundings, the more 

 we realise the fact that nature is a vast system of linkages, 

 that isolation is impossible. 



i. Dependence upon Surroundings. Every living body 

 is built up of various arrangements of at least twelve 

 " elements," viz. Oxygen, Hydrogen, Carbon, Nitrogen, 

 Chlorine, Phosphorus, Sulphur, Magnesium, Calcium, Pot- 

 assium, Sodium, and Iron. All these elements are spread 

 throughout the whole world. By the magic touch of life 

 they are built up into substances of great complexity and 

 instability, substances very sensitive to impulses from, or 

 changes in, their surroundings. It may be that living matter 

 differs from dead matter in no other way than this. The 



