350 THE INDUCTIONS OF BIOLOGY. 



equilibration, or death, were not its continually-dissipated 

 forces continually re-supplied from without. Besides owing 

 to the external world those energies which, from moment to 

 moment, keep up the lives of its individual members, every 

 species owes to certain more indirect actions of the external 

 world, those energies which enable it to perpetuate itself in 

 successive generations. 



§ 97. What evidence still remains may be conveniently 

 woven up along with a recapitulation of the argument pursued 

 through the last three chapters. Let us contemplate the facts 

 in their synthetic order. 



That compounding and re-compounding through which we 

 pass from the simplest inorganic substances to the most com- 

 plex organic substances, has several concomitants. Each suc- 

 cessive stage of composition presents us with molecules that 

 are severally larger or more integrated, that are severally 

 more heterogeneous, that are severally more unstable, and that 

 are more numerous in their kinds {First Principles, § 151). 

 And when we come to the substances of which living bodies 

 are formed, we find ourselves among innumerable divergent 

 groups and sub-groups of compounds, the units of which are 

 large, heterogeneous, and unstable, in high degrees. There is 

 no reason to assume that this process ends with the forma- 

 tion of those complex colloids which constitute organic matter. 

 A more probable assumption is that out of the complex col- 

 loidal molecules there are evolved, by a still further integra- 

 tion, molecules which are still more heterogeneous, and of 

 kinds which are still more multitudinous. What must be 

 their properties? Already the colloidal molecules are ex- 

 tremely unstable — capable of being variously modified in 

 their characters by very slight incident forces; and already 

 the complexity of their polarities prevents them from 

 readily falling into such positions of equilibrium* as results in 

 crystallization. Xow the organic molecules composed of 

 these colloidal molecules, must be similarly characterized in 



