PHYSIOLOGICAL SIGNIFICANCE OF VITAL FORCE. 763 



Logical deduction and scientific research, according to the beliefs 

 and methods of the age, permitted such doctrines to receive for a time 

 the approval of popular assent. But the spirit of inquiry was abroad 

 in the world, and the advance of embryological science soon gave the 

 demonstration that the doctrine of " included germs " had no founda- 

 tion in fact, and so it was numbered with the errors of the past. 



Cuvier, who had with such ability compared the structure of ani- 

 mal organs, and classified the facts of animal life in their statical or 

 anatomical relationship, was a " vitalist," and thought the vital prop- 

 erties of the body a kind of entity — independent of physical or chemi- 

 cal forces. 



Bichat sought, by a study of the tissues which composed the or- 

 gans, to learn the nature of their functions, or the dynamics of the 

 living body. He found that all the various kinds of tissue of the 

 body, though differing in function, were endowed with two common 

 properties — extensibility and contractility. 



While he made phenomena depend on the properties of matter, he 

 nevertheless followed Stahl as a " vitalist," and claimed that vital and 

 physical properties are not only distinct from but antagonistic to each 

 other : " The vital properties preserve the living body by counteract- 

 ing the physical properties that tend to destroy it." Each class of 

 phenomena is under distinct laws, and the conflict between them is 

 active and constant. As one or the other triumphs, life or death re- 

 sults, and " health and disease are but the vicissitudes of the strife." 



Life is, by Bichat, defined as " the group of functions that resist 

 death," and is under the direct supervision of a special principle called 

 at different times " soul," " archaeon," " psyche," or " vital force." The 

 philosophic theory which postulated this undetermined factor was 

 known by the generic term of "vitalism," which, under Stahl and 

 Bichat, took accurate definition, and deeply impressed its tenets upon 

 the physical, chemical, and physiological sciences of the age. 



Entities of some kind presided over the functions of life and the 

 manifestations of matter. A " vital principle " ruled the organic world, 

 and the phenomena of inorganic nature depended upon the presence 

 of some " principle " which existed independent of the matter through 

 which it displayed itself. Material particles, darting from luminous 

 bodies into the eye, produced the sensation of light. Heat and cold 

 depended upon the presence or absence of a material substance called 

 "caloric." Electricity was a subtile, material agent, existing in a 

 " latent " state in all substances, and manifesting great power when 

 liberated from its repose. And so throughout the domain of chemical, 

 physical, and biological phenomena, material entities existed and were 

 manifested in all forms of inorganic and organic bodies, and yet were 

 independent of them. 



This was not an age for synthetic work ; indeed, not even accurate 

 analytic work, except in simple things, could be performed. These 



