ON LIFE AND ORGANISATION. 293 



have not only been too apt to overlook the various relations to 

 which. I have already alluded, but also to keep out of view 

 certain peculiar chemico-physical characters presented by it. 

 They have been too much inclined to view its parts merely as 

 portions of a machine teleologically adapted to one another ; 

 and to neglect those structural features and distinctive actions 

 in which it differs from any ordinary mechanism. 



Organisation is never met with except as part of an organ- 

 ism — that is, of an individual material living system. 



The organism is born, or commences its life, as the pro- 

 duct of one or of two parents of like kind with itself. 

 The living organism invariably dies. 



The duration of the life of every organism is specific, 

 varying only within certain restricted limits — the causes of 

 the variation being contingent circumstances in the condi- 

 tions of its existence. 



The matter of the organised frame, to its minutest parts, 

 is in continual flux ; so that what is permanent in the 

 organism is not the matter of which it is composed, but, as far 

 as the ordinary exercise of our senses enables us to determine, 

 its form only. 



The chemical constitution of each group of the ultimate 

 organised parts of the frame is specific. In like manner, the 

 chemical constitution of each part of our ultimate organised 

 part is different. 



The ultimate chemical elements of the organism are 

 merely certain of the ultimate chemical elements of in- 

 organic matter. But the secondary, or organic chemical 

 principles, although some of them have already been pro- 

 duced artificially, and although all of them will probably 

 be ultimately formed by the chemist, are never met with 

 in nature except as the materials of, or in connection with, 

 organisation. 



The forms of living bodies, and of their parts, even of 



