BIOTIC STEUCTUEE AND BIOTIC ENEKGY 19 



In the living cell we have, however, both chemically and biotically, 

 one degree higher of complexity than any enzyme or cell product. 

 This is shown by possession of the property of self -multiplica- 

 tion or reproduction by cell division, which has not yet been shown 

 to be possible in any enzyme or toxin, although this has been mooted 

 as a possible carrier of the infection in those diseases where the 

 microscopist speaks of an ultra-microscopic germ. 



The difference between the living cell and any of its quasi living 

 products is also demonstrated by the linkage of reactions occurring 

 in the cell, and never seen in the case of enzymes or similar extra- 

 cellular substances inducing reactions. 



In spite of what is known as reversibility of enzyme action, the 

 law holds universally that an enzyme can never use energy derived 

 from one reaction to run another in which building up of energy 

 occurs, while in the living cell this is done in a thousand forms in 

 which myriads of synthesised products are built up. An enzyme 

 always runs a downhill reaction, and when it is apparently reversed 

 this really only means that the concentrations requisite for reversal 

 are such that (chiefly due to osmotic pressure variations) the 

 reversed reaction now runs downhill. 



Not to trespass too far on the work of another chapter, we may 

 put it that in the more complex organisation or colloidal structure 

 of the cell the possibility arises that work set free in one part of the 

 colloid aggregate may be used for running a reaction requiring 

 energy in another portion of the colloid. For example, oxidation 

 of carbohydrate may be running continuously with reduction 

 in another part to form higher fatty acid and fat. 



The cell is necessary for this co-ordination. If all the enzymes 

 contained within a cell were placed there without the co-ordination 

 that the cell structure gives them they might be compared to a horde 

 of savages without organisation, while the same enzymes built up 

 into the other colloidal parts of the cell become organised like a 

 disciplined army, or a civilised community, acting in a co-ordinated 

 or linked-up manner. 



In the living cell, then, we have two primary things, structure 

 and energy, and in every process of development, evolution, growth, 

 and physiological activity the energy swings the structure from one 

 phase to another, and each structural change gives rise to a corre- 

 sponding adapted energy variation. To suppose that structure 

 alone dominates the situation, and that the whole structure of the 



