ILLUSTRATION (*). VITAL FORCES. 387 



These opinions, against which the acute Yicq d'Azyr 

 has protested in his Traite d' Anatomie, vol. i. p. 5, but which 

 are still entertained by many eminent persons among my 

 friends, I have placed in the mouth of Epicharmus. Reflec- 

 tion and prolonged study m the departments of physiology 

 and chemistry have deeply shaken my earlier belief in pe- 

 culiar, so-called vital forces. In the year 1797, at the con- 

 clusion of my Versuche ilber die gereizte 2Iushel- und Nerval- 

 fascr, ?iebst Vermutlmngen ilber den chemischen Process des 

 Lebens in der Thier- und PflanzenweU (vol. ii. pp. 430 — 436), 

 I already declared that I by no means regarded the existence 

 of these peculiar vital forces as established. Since that period 

 I have not applied the term pectdiar forces to that which 

 may possibly be produced only by the combined action of 

 the separate already long known substances and their material 

 forces. We may, however, deduce a more certain definition 

 of animate and inanimate substances from the chemical rela- 

 tions of the elements, than can be derived from the criteria of 

 voluntary movement, the circulation of fluid in solid parts, 

 and the inner appropriation and fibrous arrangement of the 

 elements. I call that substance animate "whose volun- 

 tarily separated parts change their composition after separation 

 has taken place, the former external relations still continuing 

 the same." This definition is merely the expression of a fact. 

 The equilibrium of the elements is maintained in animate 

 matter by virtue of their being parts of one whole. One 

 organ determines another, one gives to another the tem- 

 perature, the tone as it were, in which these, and no other 

 affinities operate. Thus in organisation all is reciprocal, 

 means and end. The rapidity with which organic parts 

 change their compound state, when separated from a complex 

 of living organs, differs greatly according to the degree of 



inanimate, the particles of which are combined according to the laws of 

 chemical affinity. On the other hand, we call those bodies animate and 

 organic, which, although constantly manifesting a tendency to assume 

 new forms, are restrained by some internal force from relinquishing 

 that originally assigned them. That internal force, which dissolves the 

 bonds of chemical affinity, and prevents the elements of bodies from 

 freely uniting, we call vital. Accordingly, the most certain criterion 

 of death is putrescence, by which the first parts, or stamina of things, 

 resume their pristine state, and obey the laws of affinit}-. In inanimate 

 bodies there can be no putrescence." 



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