THE RELATION OF LIFE TO OTHER FORCES. 321 



dependence on ordinary physical force, but is simply stimulated by it, 

 and has no correlation with it then, indeed, it would be just to say that 

 the whole matter is merely shelved if we retain the term "vital force." 



But if a distinct correlation be recognized between ordinary physical 

 force and that which in various shapes is manifested by living beings; if 

 it be granted that every act say, for example, of a brain or muscle is 

 the exactly correlated expression of a certain quantity of force latent in 

 the food with which an animal is nourished; and that the force produced 

 either in the shape of thought or movement is but the transformed expres- 

 sion of external force, and can no more originate in a living organ with- 

 out supplies of force from without, than can that organ itself be formed 

 or nourished without supplies of matter; if these facts be recognized, 

 then the term used in speaking of the powers exercised by a living being 

 is not of very much consequence. We have as much right to use the 

 term "vital" as the words galvanic and chemical. All alike are but the 

 expressions of our ignorance concerning the nature of that power of 

 which all that we call "forces" are various manifestations. The differ- 

 ence is in the apparatus by which the force is transformed. 



It is with this meaning that, for the present, the term "vital force" 

 may still be retained when we wish shortly to name that combination of 

 energies which we call life. For, exult as we may at the discovery of the 

 transformation of physical force into vital action, we must acknowledge 

 not only that, with the exception of some slight details, we are utterly 

 ignorant of the process by which the transformation is effected; but, as 

 well, that the result is in many ways altogether different from that of any 

 other force with which we are acquainted. 



It is impossible to define in what respects, exactly, vital force differs 

 from any other. For while some of its manifestations are identical with 

 ordinary physical force, others have no parallel whatsoever. And it is 

 this mixed nature which has hitherto baffled all attempts to define life, 

 and, like a Will-o'-the-wisp, has led us floundering on through one defini- 

 tion after another only to escape our grasp and show our impotence to 

 seize it. 



In examining, therefore, the distinctions between the products of 

 transformations by a living and by an inorganic machine, we have first to 

 recognize the fact, that while in some cases the difference is so faint as to- 

 be nearly or quite imperceptible, in others there seems not a trace of' 

 resemblance to be discovered. 



In discussing the nature of life's manifestations birth, growth, devel- 

 opment, and decline the differences which exist between them and other 

 processes more or less resembling them, but not dependent on life, have: 

 been already briefly considered and need not be here repeated. It may- 

 be well, however, to sum up very shortly the particulars in which life as; 

 a manifestation of force differs from all others. 

 VOL. II. 21. 



