88 THE DATA OF BIOLOGY. 



indefinitcness that it may be suspended for a long period 

 by desiccation or freezing, and may afterwards go on as 

 though there had been no breach in its continuity. But the 

 circumstance that only a low order of life can have its 

 changes thus modified, serves but to suggest that, like the 

 previous characteristics, this characteristic of definiteness in 

 its combined changes, distinguishes high vitality from low 

 vitality, as it distinguishes low vitality from inorganic pro- 

 cesses. Hence, our formula as further amended reads thus: 

 Life is a definite combination of heterogenous changes, 

 both simultaneous and successive. 



Finally, we shall still better express the facts if, instead 

 of saying a definite combination of heterogeneous changes, 

 we say the definite combination of heterogeneous changes. 

 As it at present stands, the definition is defective both in 

 allowing that there may be other definite combinations of 

 heterogeneous changes, and in directing attention to the 

 heterogeneous changes rather than to the definiteness of their 

 combination. Just as it is not so much its chemical elements 

 which constitute an organism, as it is the arrangement of 

 them into special tissues and organs ; so it is not so much its 

 heterogeneous changes which constitute Life, as it is the co- 

 ordination of them. Observe what it is that ceases when life 

 ceases. In a dead body there are going on heterogeneous 

 changes, both simultaneous and successive. What then has 

 disappeared? The definite combination has disappeared. 

 Mark, too, that however heterogeneous the simultaneous and 

 successive changes exhibited by such an inorganic object as 

 a volcano, we much less tend to think of it as living than we 

 do a watch or a steam-engine, which, though displaying 

 changes that, serially contemplated, are largely homogeneous, 

 displays them definitely combined. So dominant an element 

 is this in our idea of Life, that even when an object is 

 motionless, yet, if its parts be definitely combined, we con- 

 clude either that it has had life, or has been made by some- 

 thing having life. Thus, then, we conclude that Life is the 



