4 Causes and Course of Organic Evolution 



charged witli positive electricity, union occurs with formation 

 of an atom. The atoms again, when electrified to varying 

 degrees, or when acted on by other forms of energy, e. g., heat 

 or light, unite into more complex particles or molecules, of 

 wliich most inorganic and all organic bodies consist. 



Such views as the above have weighty experimental facts 

 to support them, but it seems difficult if not impossible at 

 present to say whether they will be fully sustained, or whether 

 some new discovery may not modify the viewi^oint, for the 

 future. Meanwhile, it may be accepted as a working hypo- 

 thesis that facts suggest the probable primitive and universal 

 existence of only two constituents, energy as a moving, impelling, 

 molding agency, and ether particles, elastic but inert. The two 

 together constitute an electron, and when groups of them 

 vibrate or rotate at definite rates and in definite relations 

 they give rise to those bodies that we have hitherto spoken 

 of as the physico-chemical elements. 



Striking features of these elements that suggest an ultimate 

 association and possible origin in common are: that they ex- 

 hibit stages of transition from gaseous through liquid to solid 

 bodies; that when two or more unite they form a compound 

 of invariable and predicable proportion (Dalton's first law); that 

 Avhen two or more bodies unite in several proportions the 

 com})ining weights of these always bear an exact relation (Dal- 

 ton's second law); also that the law of proportional numbers of 

 Berzelius, the law of specific heat of Dulong and Petit, all con- 

 firm a definite progressive relationship between the so-called 

 elements. 



Of these elements the gaseous body hydrogen is lightest 

 and has been accepted as the unit element. 



In order to obtain, if possible, a correct picture of molecular 

 potentialities amongst living bodies, it is necessary that we 

 look into the fundamental qualities of those elements that 

 enter most largely and importantly into the constitution of 

 living matter. Of the 83 known elements, some like hydrogen, 

 oxygen, and nitrogen exist free and abundantly in nature, but 

 only in the gaseous state. Others like argon, krypton, neon. 



