THE GENERAL CONDITIONS OF LIFE 297 



the same necessity that characterises the appearance of physical 

 phenomena, when matter capable of life is present, and when the 

 external general and special conditions of life are fulfilled. In 

 other words vital phenomena are an expression of the correlation 

 of living substance and the surrounding medium, or, as Claude 

 Bernard ('79) says: "Vital manifestations result from a conflict 

 between two factors the organised living substance and the 

 medium." 



In considering this correlation the question comes up : 

 How was it with life at a time when conditions wholly different 

 from present ones prevailed upon the globe ? Was life then able 

 to exist ? When and how did it arise ? 



II. THE ORIGIN OF LIFE UPON THE EARTH 



As is well known, the earth was once in a fiery condition, like 

 the sun from which it came. The hard rocks and solid metals 

 that now compose its solidified crust were then in a molten state ; 

 its liquid nucleus was surrounded by an atmosphere of incandescent 

 gases ; its particles were in violent motion, and its temperature 

 measured thousands of degrees. 



The idea that the earth in its evolution once passed through 

 such a condition is now an accepted generality of all branches of 

 natural science. Astronomy, physics, geology, geogony, mineralogy 

 and chemistry, all agree in this. Moreover, modern science, with 

 the help of the telescope and the spectroscope, has brought the 

 fact directly before us, that even now, everywhere in the universe, 

 the same process of evolution that the earth once passed through 

 is being repeated, and that there exist upon other heavenly 

 bodies conditions analogous to each stage of the earth's evolution. 

 There now exist in space gaseous nebulae, molten spheres, and 

 solid, ice-cold masses, the last representing the present condition 

 of the moon and the future fate of the earth. 



The fact that the earth was once in a condition in which its 

 temperature was enormous and not a drop of water existed upon 

 it, in short, a condition in which the vital conditions that are^liow 

 regarded as indispensable to the existence of organisms were 

 wanting this fact will always be an important factor with whiqh 

 all speculations upon the origin of life upon the earth must deal. 

 In the light of this we will consider the various views upon the 

 origin of life that have been founded upon a scientific basis by 

 various men of science, and will endeavour to form some idea 

 respecting it, even though the idea be only a general one. 



