THE VITAL PRINCIPLE — THE BLOOD. 9 



here again a cause, not a consequence ; the truly 

 dead nerve, when vital warmth has left the 

 body, ceases to respond to the experimental 

 appliances of the physiological anatomist ; the 

 sheep, as is often to be seen, may, when just 

 slaughtered, be made to start and struggle, and 

 breathe forcibly, by means of the agency of 

 electric currents skilfully thrown upon certain 

 nerves. The frog, immediately killed, may be 

 made to leap by similar means ; but this gal- 

 vanic irritability (?wt sensibility) of the nerves, 

 and contractility of muscle, are merely the 

 remains of a power implanted in them by some 

 other principle, and are not inherent in the 

 matter composing these organs ; otherwise how 

 could it be lost ? This principle we call life, 

 or vitality, terms expressive rather of our 

 ignorance than of our knowledge. 



We have shown in a few words what life 

 does, rather than what life is. Let us see if 

 Cuvier, one of the greatest physiological ana- 

 tomists and philosophers of any age, has done 

 more. " If, in order," he says, " to obtain a 

 just idea of the essence of life, we will consider 

 it in beings wherein its effects are the most 

 simple, we shall quickly perceive that it con- 

 sists in the faculty which certain organic com- 

 binations possess of existing, during a certain 

 length of time, and under a determinate form, 

 whilst attracting continually into their compo- 

 sition a portion of surrounding matter, and 

 restoring to the elements portions of their own 

 constituent body. Life is a revolving vortex, 

 a2 



