WITH RELATION TO VITALITY. 27 



In a living system, no addition of matter can 

 produce an increase, after it has attained the 

 full perfection of its evolution. The increase 

 of bulk in common matter, is derive^ by accre- 

 tion from without. In the living system, it 

 proceeds by a power of conversion, and of secre- 

 tion from within. In the one, the whole col- 

 lected mass is irregularly heaped up, rudis indi- 

 gestaque moles : in the other, the most exquisite 

 symmetry and order mark the arrangement and 

 disposition of all its parts. The former is destitute 

 of all power of fabrication and restoration ; the 

 latter is endowed with both ; while common 

 matter, by its inertness, continues permanently 

 the same through the long course of revolving 

 years ; the latter, is in a state of perpetual mu- 

 tation and action ; and, after having attained its 

 period of perfection, perpetually verges to ine- 

 vitable decay. 



If we proceed to examine the motions which 

 are excited in an inanimate machine, however 

 simple or complicated the construction of the 

 machinery may be, and compare them with the 

 mechanical actions that flow from the power of 

 a living system, the same contrariety will be 

 found to subsist. In a hydraulic machine, the 

 water is impelled by a vis a tergo alone from 

 without :; In a living system, the fluids are pro- 

 pelled by a power from within, inherent in the 

 vessel by which the fluids are contained. In 



