86 THE DATA OF BIOLOGY. 



showing nearly as much combination in its change as a 

 plant of the lowest organization. It is ever growing and 

 ever decaying; and the rates of its composition and decom- 

 position preserve a tolerably constant ratio. It moves; and 

 its motion is in immediate dependence on its thawing. It 

 emits a torrent of water, which, in common with its motion, 

 undergoes annual variations as plants do. During part of 

 the year the surface melts and freezes alternately; and on 

 these changes depend the variations in movement, and in 

 efflux of water. Thus we have growth, decay, changes of 

 temperature, changes of consistence, changes of velocity, 

 changes of excretion, all going on in connexion; and it may 

 be as truly said of a glacier as of an animal, that by cease- 

 less integration and disintegration it gradually undergoes an 

 entire change of substance without losing its individuality. 

 This exceptional instance, however, will scarcely be held 

 to obscure that broad distinction from inorganic processes 

 which organic processes derive from the combination among 

 their constituent changes. And the reality of this distinction 

 becomes yet more manifest when we find that, in common 

 with previous ones, it not only marks off the living from the 

 not-living, but also things which live little from things which 

 live much. For while the changes going on in a plant or a 

 zoophyte are so imperfectly combined that they can continue 

 after it has been divided into two or more pieces, the com- 

 bination among the changes going on in a mammal is so 

 close that no part cut off from the rest can live, and any 

 considerable disturbance of one chief function causes a cessa- 

 tion of the others. Hence, as we now regard it. Life is a com- 

 bination of heterogeneous changes, both simultaneous and 

 successive. 



When we once more look for a character common to these 

 two kinds of vital action, we perceive that the combinations 

 of heterogeneous changes which constitute them, differ from 

 the few combinations which they otherwise resemble, in re- 



