LIFE AND LIVING BEINGS i i 



The arrest of vegetation during the winter months is due not 

 so much to the lowering of temperature as to the diminution 

 of the radiant energy received from the sun. In the same 

 way shade is harmful to vegetation, since the radiant energy 

 required for growth is prevented from reaching the plant. 



The energy radiated by the sun is accumulated and stored 

 in the plant tissues. Later on, animals feed on the plants and 

 utilize this energy, excreting the products of decomposition, 

 i.e. the constituents of their food minus the energy contained 

 in it. Thus the whole of the energy which animates living 

 beings, the whole of the energy which constitutes life, comes 

 from the sun. To the sun also we owe all artificial heat, the 

 energy stored up in wood and coal. We are all of us children 

 of the sun. 



The radiant energy of the sun is transformed by plants 

 into chemical energy. It is this chemical energy which 

 feeds the vital activity of animals, who return it to the 

 external world under the form of heat, mechanical work, 

 and muscular contraction, light in the glow-worm, electricity 

 in the electric eel. 



There is a marked difference between the forms affected 

 by organic and inorganic substances. The forms of the 

 mineral world are those of crystals — geometrical forms, 

 bounded by straight lines, planes, and regular angles. Living 

 organisms, on the contrary, affect forms which are less regular 

 — curved surfaces and rounded angles. The physical reason 

 for this difference in form lies in a difference of consistency, 

 crystals being solid, whereas living organisms are liquids or 

 semi - liquids. The liquids of nature, streams and clouds 

 and dewdrops, affect the same rounded forms as those of 

 living organisms. 



Living beings for the most part present a remarkable 

 deirree of symmetry. Some, like radiolarians and star-fish, 

 have a stellate form. In plants the various organs often 

 radiate from an axis, in such a manner that on turning the 

 plant about this axis the various forms are superposed thrice, 

 four, or more often five times in one complete revolution. 

 It is remarkable how often this number five recurs in the 



