Energies of the Organic World 69 



the action only of the recognized forms of energy, but confessed 

 the difficulty of using these so as to build up organic compounds. 



Thus Liebig says: "The capacity of elementary bodies to 

 form special combinations which are produced by plant or by 

 animal life is nothing else than chemical affinity, but the cause 

 which prevents these from uniting and from yielding to attrac- 

 tions which under other circumstances would carry them the 

 one toward the other, the cause then which arranges them in 

 living beings and assigns to them a special form, that is vital 

 force.'' 



Berzelius says: "If in the phenomena of organic chemistry 

 one understands by vital force something other than a particular 

 combination of different circumstances that bring into play the 

 normal forces of organic nature, in short if one means by that 

 a special chemical energy inherent in living bodies, one commits 

 an error Electricity, light, heat, and chemical reactions 

 unequally distributed, such are the conditions which excite 

 the elements to give rise to varied organic compounds; art 

 seeks to imitate the \atal action by making use of these con- 

 ditions, although their combinations in this case ivoiild not he as 

 perfect as in living nature'' 



But when electricity became more and more prominent as a 

 highly active and comparatively perfect form of energy; when 

 Wohler, Kolbe, Melsens, Davy, Kuhlmann, Liebig, Dumas, 

 and others succeeded — even by expenditure of much energy — 

 in building up some of the simpler crystalloid organic bodies; 

 when it was recognized that some of Graham's colloid sub- 

 stances greatly resembled— -even though greatly simpler than — 

 some organic colloids; and when substitution transformations 

 and their formulae in chemistry became more perfectly under- 

 stood, a closer bond was felt to exist between the inorganic 

 and organic kingdoms. It is fair to say also that the past 

 quarter century has greatly strengthened the bond. So during 

 the past forty to fifty years chemists and i)hysicists have gen- 

 erally agreed that the recognized forms of energy are those 

 which can sufficiently account for all biochemical changes. 



In harmony with sucli a view it might well be said that the 

 varied analytic changes which go on in plant and animal tissues, 

 such as breaking down of glucosides into sugar and other sec- 



