472 GENERAL ANATOMY. 



754. Innervation* too much restricted by those who confine 

 it to sensation and volition, holds under its dependence, in a 

 more or less distinct manner, all the phenomena of life. Modern 

 physiologists in verifying this pre-eminence of the nervous sys- 

 tem, have been enabled, supporting themselves by observations 

 in comparative anatomy and physiology, by observations on the 

 development of the embryo, and by physiological and patho- 

 logical observations and experiment, to establish some laws 

 of innervation. In general, the nervous system has so much 

 the more influence upon the rest of the organization, as the 

 animal more elevated in the series has this system more de- 

 veloped. In man the nervous system has so much the more 

 influence upon the functions, as the individual is more distant 

 from the state of an embryo, and at the same time has this sys- 

 tem farther advanced towards perfection. The influence of 

 nervous action upon another function is so much the more 

 clearly marked, as this function is further removed from the 

 state of a vegetative function. The influence of the nervous 

 centre upon the rest of the system is so much greater and 

 more necessary, as the centre is more developed, more volu- 

 minous relatively to the remainder of the system, and especially 

 as the different parts of the central mass are more exactly col- 

 lected together towards a single point; it is especially in this 

 latter respect that the nervous system of man differs from that 

 of other animals. 



755. The most elevated mental operations exercise them- 

 selves upon results, and manifest themselves through the me- 

 dium of nervous action; it is then true to say that man is an 

 intelligence served by organs. 



Actions of combination, intermediate between sensation and 

 volition, which constitute an appearance of intelligence, or the 

 advanced instinct of vertebral animals, belong also to nervous 

 action. 



* Rolando, op. cit., and Journal de physiologic, t. iii. George!, de la Phy- 

 siologic du systeme nerveux etc. Paris, 1821. Flourens, Recherches physiques 

 sur les proprietes et les fonctions du, systeme nerveux, etc.; in Archives ge- 

 ndrales de medicine, vol. ii. Fodcrc, Recher. experiment, sur le systeme 

 gerveux; in Jour, de Physiol,, torn. iii. 



