300 ATMOSPHERIC FACTOR IN EVOLUTION 



neglect the fire, which went out in the usual way, owing to want 

 of fresh fuel. But this is not, in my opinion, the full explana- 

 tion. We know that sunlight is essential to the splitting up 

 of carbon dioxide into carbon and oxygen. Surely then such 

 sunlight must have a retarding influence on the re-union of the 

 same carbon and oxygen. 



Here then we have reason for believing in a heat regulating 

 centre in the fire, or rather in every atom of carbon and oxygen, 

 regulating their degree of chemical aflfinity for each other. We 

 see, then, that this heat regulating mechanism is not confined 

 to living organisms, but extends to so-called dead, inorganic 

 matter. 



I have said that as change of temperature was the dominant 

 factor in inorganic, so change of food was the dominant factor 

 in organic evolution. I have also said that as heat was the 

 most important condition to the inorganic, so was food the most 

 important to the organic. We have some reason to believe 

 that inorganic matter has a heat regulating centre ; so, by 

 analogy we would expect the organic to have something higher, 

 and more appropriate to its increased needs ; that is a food or 

 nourishment regulating centre, very analogous to the old heat- 

 regulating centre and exercising its control in a similar way. 

 The old recognised heat-regulating centre in animals, controls 

 the heat of the body mainly by (i) regulating the amount of 

 evaporation, that is the cooling process, or (2) by increasing the 

 oxidation of the carbon of the food by the oxygen in the air 

 respired, that is the warming process. We see, then, that, in 

 animals, as we have already seen in plants, the heat regulating 

 processes are really parts of the nutritive processes ; the only 

 difference between the plants and the animals being that the 

 main nutritive process in the plant, the splitting up of carbon 

 dioxide is a cooling process, whereas, as was to be expected, the 

 reverse process, the re-uniting of carbon and oxygen in animals 

 is a warming process just as it was in the fire ; the more sun 

 and the more heat, the less readily do the two re-unite to form 

 carbon dioxide. 



We see, then, that the new food regulating centre is prac- 

 tically after all our old established friend the heat-regulating 

 centre, but with a new name. 



The general law, then, for which we have been in search, the 

 law in accordance with which organic evolution has been brought 

 about, is as follows : — (This, too, expresses my new theory 

 of evolution.) 



In every organism there is a food regulating (or as I prefer to 

 name it) a nurture regulating centre, which is constantly receiving 

 an ever varyng account of every condition, internal and external 

 to the organism, and is as constantly adapting the organism to 

 these varying conditions by regidating the nurture of the various 

 parts in the way that is best for the organism as a whole. 



I simply take the old recognised heat regulating centre, and 

 give it a new name. 



According to my theory, this centre is a kind of central bureau 

 which is constantly posted up in every circumstance affecting the 



