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THE AMERICAN NATURALIST [Vol. XLII 



things, a vital force (or energy, as we would call it 

 to-day), differing in nature from the forces (or forms of 

 energy) that exist in non-living things. Johannes Miiller 

 presented the vitalistic conception clearly as follows : 



to form one compound, which is observed only in organic bodies, and 

 in them only during life. Organized bodies, moreover, are constituted 

 of organs, . . . each . . . having a separate function; . . . and 

 they not merely consist of these organs, but by virtue of an innate 

 power, they form them within themselves. Life, therefore, is not 

 simply the result of the harmony and reciprocal action of these parts; 

 but is first manifested in a principle or imponderable matter, which 

 is in action in the substance of the germ, enters into the composition 

 of the matter of the germ, and imparts to organic combinations prop- 

 erties which cease at death." 



By the same author life is characterized as "the mani- 

 festation of the organic or vital force." Again, "Or- 

 ganic bodies participate in the general properties of 

 ponderable matter. The laws of mechanics, statics and 

 hydraulics are also applicable to them." The applica- 

 tion of these laws to them is, however, "limited," from 

 the circumstance that the causes of motion most engaged 

 in them are essentially vital in their nature." A few 

 bold spirits, like Keil in Germany and Magendie in 

 France, argued against such a conception, but they 

 formed a small minority, and the physiology of the time 

 became essentially vitalistic. 



This state of affairs prevailed for barely a century. 

 Soon after its beginning oxygen was discovered, and the 

 modern chemistry was begun. A few decades more and 

 the new physics was founded on the doctrine of the con- 

 servation of energy. These two discoveries with their 

 momentous consequences were epoch-making for physi- 

 ology. The events of the inorganic world were at last 

 conceived by the human mind in a rational manner, and 

 the application of such conceptions to vital processes was 

 not delayed. The assumption of a specific vital force 

 was seen to be unnecessary. Men began to talk of vital 

 phenomena in terms of the new sciences, and physiology 



