186 THE WORLD OF LIFE chap. 



minating in man, in any other known or reasonably conjec- 

 tured planet, but affords, in my opinion, an exceedingly 

 powerful argument for an overruling MlND, which so ordered 

 the forces at work in the material universe as to render the 

 almost infinitely improbable sequence of events to which I 

 have called attention an actual reality. 



Terrestrial Temperature-A adjustments 



Among the many wonderful adjustments in the human 

 body, and in that of all the higher vertebrates, none perhaps 

 is more complex, more exact, and apparently more difficult 

 of attainment than those which preserve all the circulating 

 fluids and internal organs at one uniform temperature, vary- 

 ing only four or five degrees Fahr., although it may be ex- 

 posed to temperatures varying more than a hundred degrees. 

 Hardly less wonderful are those cosmical and physical 

 adjustments, which, during many millions of years, have 

 preserved the earth's surface within those restricted ranges of 

 temperature which are compatible with an ever-increasing 

 development of animal and vegetable life. 



Equally remarkable, also, is that other set of adjustments 

 leading to those perpetual surface-changes of our globe which 

 I have shown to be the motive power in the development of 

 the marvellously varied world of life ; and which has done this 

 without ever once leading to the complete subsidence of any 

 of the great continents during the unceasing motions of 

 elevation and depression which have been an essential part 

 of that great cosmic scheme of life-development of which I 

 am now attempting an imperfect exposition. 



That the temperature of the earth's surface should have 

 been kept within such narrow limits as it has been kept 

 during the enormous cycles of ages that have elapsed since 

 the Cambrian period of geology, is the more amazing when 

 we consider that it has always been losing heat by radiation 

 into the intensely cold stellar spaces ; that it has always, and 

 still is, losing heat by volcanoes and hot springs to an 

 enormous extent ; and that these losses are only counteracted 

 by solar radiation and the conservative effect of our moisture- 

 laden atmosphere, which again depends for its chief conserva- 

 tive effect on the enormous extent of our oceanic areas. 



j 

 I 



