CHAPTER V. 



THE ANIMAL FUNCTIONS. 



SECTION I. A SHORT ENUMERATION OF THEM. 



In that portion of the nervous system which we have termed 

 the sensorium commune^ such a mechanism lies concealed, that 

 external sensory impressions of the nerves are reflected in it 

 upon the motor nerves in a singular manner, and by unerring 

 and peculiar laws, so that they produce distinct and definite 

 movements of the muscles. It has already been stated, that 

 many motions truly automatic take place in man by means of 

 this vis nervosa of the sensorium commune only; nevertheless, 

 although many animals which are destitute of brain, and the 

 higher endowments of animals are regulated and live only 

 through this vis of the sensorium commune, and therefore may 

 be termed true automata, in man and many allied animals the 

 nervous system is increased by the addition of a brain; and 

 moreover, with a certain principle which we call the soul, an ens 

 of incorporeal origin, and which we are taught by faith to have 

 been granted to man alone, to constitute him an immortal crea- 

 ture by the special favour of God. So long as the soul is joined 

 with the body, it manifestly produces no operation which depends 

 solely and exclusively upon itself, but all take place by means 

 of the nervous system as the instrument; so that in all the animal 

 functions, the nervous system has a share as the instrument, 

 and the mind a share as the acting and determining principle. 



Animal actions under the name of internal senses, or under 

 the name of faculty of thought, or of reason, or of intellect, 

 come continually under the observation of physicians. I by 

 no means propose to treat of these so accurately and profoundly 

 as has been done by metaphysicians and psychologists, but 

 only to touch on those points with which it behoves physicians 

 to be fully acquainted. The principal divisions into which the 

 animal functions may be conveniently divided, are perception, 

 understanding, and will, to which may be added imagination and 

 recollection, or memory, 



