6 IRRITABILITY 



system. "Sola fibra muscularis contrahitur vi viva; sentit solus 

 nervus et quce nervos acciperunt animates partes." By confining 

 the conception of irritability to a single living substance, the 

 muscle, Hatter's theory represents a great regression in compari- 

 son to the correct fundamental thoughts of Gtisson. This unfor- 

 tunate use of the term of "irritability," "contractility" and 

 "sensitivity" has opened wide the gates to confusion and mis- 

 understanding. This confusion was still further augmented by 

 the fact that the vitalistic school of Montpelier confused the idea 

 of vital force with that of irritability. In the works of Bordeu 

 (1732-1776) these views are comparatively clear, if one bears 

 in mind that he substitutes Gtisson's term of "irritability" with 

 that of "sensitivity." He assumes a "sensibilite generale" or a 

 common property of all living structures, both solid and fluid. 

 Besides this, each different part has according to him its "sensi- 

 bilite propre." Here in place of the clear conception of irri- 

 tability we find one of more or less mythical nature possessing 

 traces of Stahl's "anima." Nevertheless we observe here the 

 idea that all living organisms possess in common a capability to 

 respond to stimuli. Even though Bordeu's differentiation of the 

 "sensibilite propre" and the "sensibilite generale" is too artificial 

 and the coexistence of both not justifiable, his discussion of the 

 "sensibilite propre" shows that he is already on the track of the 

 characteristics of the effect of stimuli which only later under the 

 name of "specific energy" was clearly recognized as a funda- 

 mental property of all living substance. On the other hand the 

 celebrated pupil of Bordeu, Barthez (1734-1806), accepted the 

 existence of a meaningless vital principle, the "principe vitale" 

 governing all vital manifestations. The two forms of vital force 

 of all living substances, the "forces sensitives" and the "forces 

 motrices" were according to his views manifestations of this 

 vital principle. He differentiates the "force sensitive" into a 

 "sensibilite avec perception" and "sensibilite sans perception," 

 using the term sensibility in the sense adopted by Bordeu and 

 which today we, with Glisson, call irritability. 



In this way serious thinkers of that time trifled with the words 

 irritability, sensitivity, contractility, perception. This led to 



