EVOLUTION THE RESULT OF CHEMICAL FORCES. 95 



to build them up into those wonderful molecules that are 

 laid away in cereals and other seeds for the nourishment of 

 vegetable germs. These substances, variously known as fibrin, 

 glutin, legumin, &c., have thus become veritable reservoirs of 

 sun-power. When taken into the animal system as food, they 

 are carried through the digestive processes into the blood, and by 

 the blood are laid away in the muscles, brain, and various tissues 

 of the body, where as occasion requires they are burned up again 

 in the oxygen of respiration, precisely as wood and coal are 

 burned to generate mechanical power. This is the epitome of 

 the history of all vital phenomena. The radiant energy of the 

 sun builds up a frail and complex structure, which the animal 

 economy tears to pieces ; and as the atoms fall off from this 

 microcosmic pile in the living organism, and yield up their forces 

 to the body politic, there is life and impulse and intelligence. If 

 it were not for the unique capacity of the carbon element to be 

 thus enormously accumulated in the electric batteries of organic 

 molecules, there would be, so far as we can judge, no possibility 

 of life. 



From the consideration of several facts in chemical physics it 

 is reasonable to conclude that the atoms of all elemental bodies 

 and the molecules of all compound bodies are very nearly if not 

 exactly of the same size. Equal measures of all gases, no matter 

 how heavy or how light, contain the same number of atoms or 

 molecules. A cubic inch for instance of the vapor of aluminic 

 iodide, which weighs 408 times as much as the same measure of 

 hydrogen, contains just as many molecules as a cubic inch of air, 

 oxygen, hydrogen, or any other gas, under the same temperature 

 and pressure. Now the law of the equal contraction in bulk of 

 all gases under the same weight of compression or lessening of 

 heat, could not very well hold good if there was such an enor- 

 mous difference in the sizes of molecules and atoms as there is in 

 their weights. Again in solids, where the atoms are supposed to 

 be nearly in contact, there is a very considerable correspondence 

 between the atomic weights and the specific gravities of sub- 

 stances. Thus aluminum with an atomic weight of 27.5 and a 

 specific gravity compared with water of 2.6, shows nearly the 



