1861.] Vegetable and Animal to the Inorcfanic Kingdom. 369 



waste and repair whereby the^condition is maintained, notwithstanding 

 constant change. 



Life is not a state of resistance. The proofs of this are clear and 

 complete. Waste or destruction is a necessary, an inevitable condition 

 of its manifestation. It is involved in every vital act. And the power 

 of compensating for this waste or change, the repair or reproduction 

 necessary to the continuance of life, involves that of assimilation, — the 

 power of converting foreign matters into the structure of the organism : 

 in other language, the power of appropriating food. 



We cannot conceive life without including these two conditions — 

 consumption and supply. Life is not a state of change only, as op- 

 posed to stability ; for this is simply a question of degree everywhere, 

 and dependent on the conditions to which bodies are exposed. Neither 

 dead organic nor inorganic bodies are immune from change. Nor is 

 life peculiar as a process of repair only ; for this may occur in inor- 

 ganic bodies, as crystals, under favourable circumstances. But in life 

 there is the constant and concurrent operation of these two processes, 

 whereby it is distinguished from mere change on the one hand, and 

 from repair on the other. 



It does not appear that we can at present safely venture further 

 than this. If we attempt to define the vital process of nutrition, dis- 

 tinctions fail us. 



The investigation of the phenomena of life has not been in any way 

 assisted, our knowledge of the vital processes has not been in any 

 measure advanced, by the assumption of what has been styled a " vital 

 principle ;" — an empirical term, which, like some others when employed 

 in physiology, is, even at the best, equivalent to nothing more than the 

 final letters of the alphabet in an algebraical formula : for it is, when 

 used in its least objectionable sense, a mere expression of something 

 unknown. But the assumption of such an agent or principle, how- 

 ever designated, annihilating or suspending the operation of forces 

 acting elsewhere, has not proved altogether harmless in its influence 

 upon the progress of knowledge. By referring all vital actions to this 

 obscure agency, while nothing was thereby explained, inquiry was to a 

 great extent, and for a long while, checked. Many, dazzled by the 

 idea that the nature of vital phenomena was exalted by thus associat- 

 ing them with some mysterious and peculiar principle apart from, and 

 opposed to those agencies which act elsewhere, missed the grander con- 

 ception, that even in the vital functions may be recognized the operation 

 of forces, some of which, at least, are common to both kingdoms of 

 nature ; while, between these and others, which appear to be peculiar 

 to living tissues, it is probable that a relation may exist like that which 

 prevails between the chemical and physical forces. 



Again, it is needful to beware how we create artificial distinctions. 

 Is there not much assumption involved in the confession that we are 

 unable to construct the simplest form of living tissue ? Men some- 

 times talk as if their powers were limited only by life. But can we 

 construct a crystal any more than a nucleated cell ? We may fulfil 

 Vol. IIL (No. 34.) 2 c 



