PAPERS PRESENTED AT GENERAL SESSIONS 67 



mology as is the energies of the stars, for the stars feed 

 upon it in exactly the same sense that the cattle feed 

 upon the grass of the fields. We have already assumed 

 that the atom breaks down in the interior of a star, and 

 that when a jDositive nucleus and a negative electron 

 collide and unite their electrical energies disappear in 

 radiation and a new physical unit appears which has 

 properties different from the atom. In particular this 

 new unit is not subject to the law of gravitation and it 

 therefore parts company with the star. It has served its 

 purpose and is now a waste product. If this assumption 

 is correct then space must be more or less filled with such 

 units. AVhat role they may play in what we call ' ' empty 

 space" (really, it is not to be supposed that space is 

 any^vhere "empty") would be difficult to say unless per- 

 haps they constitute the units of that unsubstantial some- 

 thing which we call the ether. They may transmit ener- 

 gy even though they possess no mass. Let us suppose 

 that this is so and that these units are affected by the 

 energy which is radiating through space. Then it may 

 happen upon an excessively rare occasion when the con- 

 ditions are just right that one of these units is separated 

 again into the two parts which had originally united and 

 it returns again to the atomic state. The properties of 

 mass and gravitation are restored and a certain amount 

 of radiant energy has disappeared — exactly the same 

 amount which the atom had contributed to the radiation 

 of some star. 



It would be idle to speculate upon the details of this 

 process of restoration. We know that the radiant ener- 

 gy of the sun builds up the organic molecules of the 

 vegetable world from the inorganic molecules. The 

 cattle feed upon the vegetation, and the molecular ener- 

 gies appear in the motions and activities of the animals. 

 Sooner or later these energies again take the radiant 

 form and pursue their journey through space. The 

 waste products of the cattle, including finally the body it- 

 self, are scattered over the fields and through the air. 

 Again they become inorganic molecules, ready upon 

 some rare occasion to take up a portion of the sun's ra- 



