304 TRANS. OF THE ACAD. OF SCIENCE. 



forces are concerned, acts therefore the most important 

 part in the processes of organic life. But besides chemical 

 affinity, other physical forces, indispensable to organic life, 

 must not entirely be overlooked, to Avit : heat, light and elec- 

 tricity. 



" Without the light of the sun (says Liebig,) plants cannot 

 grow. Sunlight acts in living plants like electricity, which 

 arrests the natural attraction of the elements of water, and 

 separates them from each other. The living germ, the green 

 leaf, owe to the sun their power of transferring earthly ele- 

 ments into living, vigorous structure. The germ may, indeed 

 be evolved underground without the action of light, but only 

 when it breaks through the surface of the soil does it first 

 acquire the power, by the sun's rays, of converting inorganic 

 elements into its own structure. Their power now becomes 

 latent in the new products of the frame, which have been 

 produced, under their influence, from carbonic acid, water, 

 and ammonia. Man, by food, not only maintains the perfect 

 structure of his body, but he daily lays in a store of power 

 and heat, derived in the first instance from the sun. The 

 rays of the sun add daily to the store of indestructible forces 

 of our terrestrial body, maintaining life and motion." 



The near relationship between the action of our nervous 

 system and electricity has often been commented upon, and 

 also experimentally proved by Matteuci and others. Though 

 not identical, the two forces seem to be correlated. Ner- 

 vous action can be induced by electricity, and electricity can 

 be produced, as for instance, in the electric eel, by nervous 

 influence. The phenomena, also, of catalysis, the processes 

 of endosmosis and exosmosis, in the living body, are depend- 

 ent upon voltaic action. But as the principal actor in the 

 processes of organic life, so far as physical forces are con- 

 cerned, we acknowledge at present chemical affinity. 



Organic chemistry has, within this century, made wonder- 

 ful progress ; it has not only unravelled many mysteries 

 inside the organic bodies, but it has succeeded even in fabri- 

 cating, outside of them, in the chemical laboratory, some 

 compounds, which nature produces only in organic bodies. 

 This partial success has led some physiologists to another 

 illusion, to wit : that chemistry has not developed to us a 

 new mode of action in organic bodies, but the moving power 

 itself; that organic chemistry has revealed the last cause of 

 action in organic life, and that vital force is an absolute " hum- 

 bug." Having discovered the hands moving over the dial 

 plate, they imagine they comprehend now thoroughly the 

 propelling force within. This, in my opinion, is as great a 

 mistake as the first was. From all the various, complicated 

 chemical processes in a living body no organic action would 

 ensue, if there was not a higher power behind, that harmon- 



