66 THE DATA OF BIOLOGY. 



mostly mechanical actions that are to a great degree similar ; 

 and in this respect widely differ from the actions of any mo- 

 ment taking place in an organism : which not only belong to 

 the several classes, mechanical, chemical, thermal, electric, but 

 present under each of these classes, innumerable unlike actions. 

 Even where life is nearly simulated, as by the working of a 

 steam-engine, we may 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 exhi- 

 bited by a living creature. Still, it will be found that 

 this peculiarity, like the foregoing ones, does not divide the 

 two classes of changes with precision ; inasmuch as there are 

 inanimate things which exhibit considerable heterogeneity of 

 change : for instance, a cloud. The variations of state which 

 this undergoes, both simultaneous and successive, are many 

 and quick ; and they differ widely from each other both in 

 quality and quantity. At the same instant there may occur 

 in a cloud, change of position, change of form, change of 

 size, change of density, change of colour, change of tem- 

 perature, change of electric state ; and these several kinds of 

 change are continuously displayed in different degrees and 

 combinations. Yet notwithstanding this, when we consider 

 that very few inorganic objects manifest heterogeneity of 

 change in a marked manner, while all organic objects mani- 

 fest it ; and further, that in ascending from low to high forms 

 of life, we meet with an increasing variety in the kinds and 

 amounts of changes displayed ; we see that there is here 

 a further leading distinction between organic and inorganic 

 actions. According to this modified conception, then, Life is 

 made up of heterogeneous changes both simultaneous and 

 successive. 



If now we look for some point of agreement between the 

 assimilative and logical processes, by which they are distin- 

 guished from those inorganic processes that are most like 

 them in the heterogeneity of the simultaneous and successive 



