BIONOMICS 249 



system as a consequence. That is to say that activity, i.e., 

 work, is a necessary condition of the maintenance of status. 



As regards the overthrow of the nervous equilibrium by 

 vegeto-alkalies, we have previously seen that we have here not 

 merely " special molecular actions," but that symbiotic factors 

 are fundamentally concerned. In short, whether " the condi- 

 tions of rapid molecular change throughout the body " are well 

 or ill-fulfilled depends entirely on biological factors. If this 

 is true of so many kinds of " insensible motion," it is far more 

 true of "sensible motion." 



"It is indeed usual," continues Spencer, "to regard the 

 power of generating sensible motion as confined to one out of 

 the two organic sub-kingdoms ; or, at any rate, as possessed by 

 but few members of the other. On looking closer into the 

 matter, however, we see that plant-life as well as animal-life 

 is universally accompanied by certain manifestations of this 

 power; and that plant-life could not otherwise continue." 



This he infers from the facts of "an internal transposi- 

 tion of parts" in plants and of "the mutual dependence of 

 organs having unlike functions," and of the "shooting out of 

 pollen by some flowers on to the entering bee when its trunk 

 is thrust down in search of honey," i.e., from obvious 

 symbiotic arrangements. Hence he thinks that on the produc- 

 tion of this " mode of force " (i.e., "sensible motion "), more 

 especially depends the possibility of all vital phenomena. The 

 power of "sensible motion " is thus seen to be identical with 

 the general power to be symbiotic. 



Spencer is satisfied that his study of the reactions of 

 organic matter on forces has yielded the result he required, 

 viz., the confirmation of one of his physico-chemical First 

 Principles : the persistence of force. 



Whatever amount of power an organism expends in any shape is 

 the correlate and equivalent of a power that was taken into it from 

 without. On the one hand, it follows from the persistence of force, 

 that each portion of mechanical or other energy which an organism 

 exerts, implies the transformation of as much organic matter as con- 

 tained this energy in a latent state. And on the other hand it follows 



