T6 LAY SERMONS ADDRESSES, AND REVIEWS. [v 



form, but is essentially distinguished as a disturber 

 of equilibrium so far as force is concerned, — as under- 

 going continual metamorphosis and change, in point of 

 form. 



Tendency to equilibrium of force and to permanency 

 of form, then, are the characters of that portion of the 

 universe which does not live — the domain of the chemist 

 and physicist. 



Tendency to disturb existing equilibrium — to take on 

 forms which succeed one another in definite cycles — is 

 the character of the living world. 



What is the cause of this wonderful difference between 

 the dead particle and the living particle of matter 

 appearing in other respects identical % that difference 

 to which we give the name of Life 1 



I, for one, cannot tell you. It may be that, by and 

 by, philosophers will discover some higher laws of which 

 the facts of life are particular cases — very possibly they 

 will find out some bond between physico-chemical 

 phsenomena on the one hand, and vital phenomena 

 on the other. At present, however, we assuredly know 

 of none; and I think we shall exercise a wise humility 

 in confessing that, for us at least, this successive assump- 

 tion of different states — (external conditions remaining 

 the same) — this spontaneity of action — if I may use 

 a term which implies more than I would be answerable 

 for — which constitutes so vast and plain a practical 

 distinction between living bodies and those which do 

 not live, is an ultimate fact ; indicating as such, the 

 existence of a broad line of demarcation between the 

 subject-matter of Biological and that of all other sciences. 



For I would have it understood that this simple 

 Euglena is the type of all living things, so far as the 

 distinction between these and inert matter is concerned. 

 That cycle of changes, which is constituted by perhaps 



