232 ON VAEIABILITY AND ADAPTATION 



easily break off certain side-chains already attached, thereby 

 giving off energy, which as easily, under certain conditions of 

 environment, attach other side-chains to them in definite order, 

 thereby storing up energy and undergoing growth. 



I would dwell for a moment upon this point made by Earl, 

 and abeady referred to, namely, the remarkable condition of 

 persistent, unstable equilibrium of living as distinguished from 

 non-living matter. The distinction, I would say, not so absolute 

 as he lays down. Once more, it is a matter of degree. Non- 

 living matter is only in a condition of relatively stable equilibrium. 

 Our earth, for instance, taken as a unit, is only relatively stable. 

 If astronomy teaches anything, it is that each planet, each sun, 

 each solar system, has its periods ; that each begins in a gaseous 

 state, a state of enormous instability, enormous liberation of 

 energy ; that from the nebulous stage, as a result of the mutual 

 attraction and combination of its elements, it undergoes a stage 

 which is strictly comparable to that of growth and then settles 

 down into partially- — and only partially — independent systems, 

 with a certain storage and a certain dispersal of energy. But 

 our earth, for instance, is subject to progressive change, and is 

 far from being eternal. Sooner or later in the aeons that are to 

 come, our sun will become exhausted as an energy-distributing 

 centre ; the system will be dead. Sooner or later, in aeons far 

 far distant, the attraction ever present between planet and sun, 

 and sun and other suns of yet greater systems, will draw planet 

 unto sun, and sun unto other suns, and with each act, so colossal 

 will be the force exerted, the force of impact, that what is now 

 solid and fixed will once more be dissipated ; the equilibrium is 

 but temporary, the return to the nebulous stage inevitable. 



But true it is, all the same, that the equilibrium of living 

 matter is most markedly unstable, and this instability is essential 

 for active dynamic life. We are never satisfied. Eender the 

 living molecule a satisfied body, with all its side-chains complete, 

 and unable to make attachments with other ions, so that no 

 further interactions are possible between the molecular system 

 and its environment, and it must come to rest, and function be 

 at a standstill, all indications of life ceasing. It is quite possible 

 that, as Gowers indicates, certain poisons act, and thereby induce 

 death, by combining with the molecules of certain all-important 

 centres in such a way as to satisfy those molecules, and so arrest 



