908 CONTRADICTORY OPINIONS 



of the atmosphere, give rise to animal heat," 

 that " by means of nerves, all parts of the body, 

 all the limbs, receive the moving force which 

 is indispensable to their functions, to change of 

 place, to the production of mechanical effects," 

 that " where nerves are not found, motion does 

 not exist," that " the excess of force generated 

 in one place, is conducted to other parts by the 

 nerves, and that " from the unequal degree of 

 conducting power in the nerves, we must deduce 

 those conditions which are termed paralysis, syn- 

 cope, and spasm." (Vol. ii. pp. 3, 30, 219, 230.) 



Yet in opposition to all these assertions, (which 

 are refuted by the well known existence of mo- 

 tion in plants, and in many of the lower animals 

 that have no nerves,) he maintains in the same 

 volume, that " the only known ultimate cause of 

 vital force, either in animals or plants, is a chemi- 

 cal process:" that " the ultimate cause of all the 

 forces in the animal body is a change of material 

 particles by the conversion of food into oxidized 

 products," that " the process of chymification 

 is independent of the vital force, and is purely a 

 chemical action,"* (pp. 30, 32, 34, 108.) 



But in direct contradiction of all these state- 



* It is very true, that food may be converted into chyme by the 

 chemical action of gastric juice alone, even out of the stomach, 

 if kept at the temperature of the body, as demonstrated by the 

 experiments of Dr. Beaumont and others. But does Liebig really 

 believe, that the secretion of gastric juice is not as much a vital 



