314 SIMPLE AND COMPOUND EVOLUTION. 



go on producing leaves and flowers. We see, too, that their 

 seeds, to which light is not simply needless but detrimental, 

 begin to germinate only when the return of a warm season 

 raises the rate of molecular agitation. In like manner the 

 ova of animals, undergoing those changes by which struc- 

 ture is produced in them, must be kept more or less warm: 

 in the absence of a certain amount of motion among their 

 molecules, the re-arrangement of parts does not go on. 

 Hybernating animals also supply proof that loss of heat car- 

 ried far, retards extremely the- processes of transformation. 

 In animals which do not hybernate, as in man, prolonged 

 exposure to intense cold produces an irresistible tendency to 

 sleep (which implies a lowered rate of structural and func- 

 tional changes); and if the abstraction of heat continues, 

 this sleep ends in death, or stoppage of these changes. 



Here, then, is an accumulation of proofs, general and 

 special. Living aggregates are distinguished by the con- 

 nected facts, that during integration they undergo very 

 remarkable secondary changes which other aggregates do 

 not undergo to any considerable extent; and that they con- 

 tain (bulks being supposed equal) immensely greater quan- 

 tities of motion, locked up in various ways. 



105. The last chapter closed with the remark that 

 while Evolution is always an integration of Matter and dis- 

 sipation of Motion, it is in most cases much more. And 

 this chapter opened by briefly specifying the conditions 

 under which Evolution is integrative only, or remains 

 simple, and the conditions under which it is something 

 further than integrative, or becomes compound. In illus- 

 trating this contrast between simple and compound Evolu- 

 tion, and in explaining how the contrast arises, a vague 

 idea of Evolution in general has been conveyed. Unavoid- 

 ably, we have to some extent forestalled the full discussion 

 of Evolution about to be commenced. 



There is nothing in this to regret. A preliminary con- 



