56 ORGANIC FUNCTIONING 



The accessory activities of reproduction are individual ones : 

 thus courtship, copulatory actions, spawning, parturition and 

 the nutrition and care for the progeny are to be regarded as 

 individual behaviour. But the essential acts of reproduction — 

 that is, the divisions and maturations of the germ-cells, etc., 

 are racial activities and will be discussed specially (see Sections 

 6s, 66). 



So also the processes of sensation, of central nervous activi- 

 ties, of cerebral co-ordination, of ancestral and individual ex- 

 perience and of memory must be discussed specially (Chapter 



IV). 



In the study of organic functioning, as it is taken up in this 

 chapter, we deal largely with energy- transformations. Therefore 

 a preamble on energy in general is necessary and to this we proceed 

 immediately. 



/. A PREAMBLE ON ENERGY 



16. ENERGY IN GENERAL 



There is a necessary condition that any ph3^sical change what- 

 ever may occur : this is the existence of available energy in the 

 system of things in which the change occurs. 



Thus available energy is, in the ordinary sense, the cause of 

 physical changes, and when we measure the quantity of it that 

 is contained in a system of things we also measure the quantity 

 of physical causality exhibited by the system. 



Energy (still in the available mode) is recognized by us in these 

 states of things : 



(i) In the familiar world. In the rotation of the earth, 

 the gravitational attraction on earthly things exercised by the 

 sun and moon, and in the heat of the sun — these conditions 

 give us the tides, ocean currents, winds, running water, 

 glaciers and icebergs ; in the gravitation of things to the earth 

 itself. 



In atmospheric electricity and terrestrial magnetism ; 



In the internal heat of the earth that comes from its original 

 condition and from the radioactivity of its materials ; 



In the chemical substances of the earth's crust and waters and 

 atmosphere ; coal, oil and all the materials that can interact 

 with each other ; and so on. 



