84 THE BATA OF BIOLOGY. 



low vitality. It needs but to contrast the many organs co- 

 operating in a mammal, with the few in a polype, to see that 

 the actions which are progressing together in the body of the 

 first, as much exceed in number the actions progressing to- 

 gether in the body of the last, as these do those in a stone. As 

 at present conceived, then. Life consists of simultaneous and 

 successive changes. 



Continuance of the comparison shows that vital changes, 

 both visceral and cerebral, differ from other changes in their 

 heterogeneity. Neither the simultaneous acts nor the serial 

 acts, which together constitute the process of digestion, are 

 alike. The states of consciousness comprised in any ratio- 

 cination are not repetitions one of another, either in com- 

 position or in modes of dependence. Inorganic processes, on 

 the other hand, even when like organic ones in the number 

 of the simultaneous and successive changes they involve, are 

 unlike them in the relative homogeneity of these changes. 

 In the case of the sea, just referred to, it is observable that 

 countless as are the actions at any moment going on, they are 

 mostly mechanical actions that are to a great degree similar; 

 and in this respect differ widely from the actions at any 

 moment taking place in an organism. Even where life is 

 nearly simulated, as by the working of a steam-engine, we 

 see that considerable as is the number of simultaneous 

 changes, and rapid as are the successive ones, the regularity 

 with which they soon recur in the same order and degree, 

 renders them unlike those varied changes exhibited by a 

 living creature. Still, this peculiarity, like the fore- 



going ones, does not divide the two classes of changes with 

 precision; since there are inanimate things presenting con- 

 siderable heterogeneity of change: for instance, a cloud. 

 The variations of state which this undergoes, both simulta- 

 neous and successive, are many and quick; and they differ 

 widely from one another both in quality and quantity. At 

 the same instant there may occur change of position, change 

 of form, change of size, change of density, change of colour, 



