136 SIMPLER ORGANIC SUBSTANCES 



body. When the mass of this body became great enough the 

 necessary conditions were created within it for the setting 

 up of the carbon cycle whereby hydrogen is converted into 

 hehum ; this resulted in the liberation of enormous amounts 

 of intra-atomic energy so that the body became a star giving 

 off light, the Sun. The further development of the Sun 

 proceeded according to the curve of the main sequence in 

 the Hertzsprung-Russell diagram (Fig. 10).^" The remain- 

 ing matter of the globule which did not enter into the 

 constitution of the Sun formed itself into a discoid cloud of 

 dust and gas from which the protoplanets were formed. 



Contemporary cosmogonic literature contains a large 

 number of hypotheses which try to explain the mechanism of 

 the formation of planets. 



These are based on the rotary motion, gravitational forces 

 and other physical phenomena which arise when particles of 

 gas and dust collide. 



The motion of the particles in the primaeval planetary 

 cloud was chaotic. The particles revolved independently 

 around the central body as very small satellites in different 

 directions and planes. In the course of their motion they 

 inevitably collided with each other. However, because the 

 collisions between the solid particles or between particles of 

 dust and molecules of gas were inelastic, it follows that as the 

 kinetic energy was transformed into other forms of energy 

 the total amount of kinetic energy in the planetary cloud 

 diminished as time went on. Mathematical analysis of the 

 development of the planetary cloud under these conditions 

 shows that this proceeds by the flattening out of the cloud 

 and the gradual amalgamation of the material which was 

 originally scattered through space into relatively small bodies 

 (planetesimals), then into coarser formations made up of 

 centres in which the material is collected together and finally 

 into planets.^"" 



Ways in which organic compounds could 

 have arisen during the formation of 

 the Earth. 



Most authors devote themselves almost exclusively to the 

 study of the physical aspects of the subject and try to explain 



