﻿204 Proceedings of the Royal Physical Society. 



of facilities. It is, therefore, possible to say that as the 

 cell grows "it must get into physiological difficulties, for 

 the nutritive necessities of the increasing mass are ever 

 less adequately supplied by the less rapidly increasing 

 absorbent surface. The early excess of repair over waste 

 secures the growth of the cell. Then a nemesis of growing 

 wealth begins. The increase of surface is necessarily dis- 

 proportionate to that of content, and so there is less oppor- 

 tunity for nutrition, respiration, and excretion. Waste 

 thus gains upon, overtakes, balances, and threatens to 

 exceed repair. Suppose a cell to have become as big as 

 it can well be, a number of alternatives are possible. 

 Growth may cease, and a balance be struck. On the other 

 hand, waste may continue on the increase, and bring about 

 dissolution and death ; while closely akin to this there 

 is the most frequent alternative, that the cell divide, halve 

 its mass, gain new surface, and restore the balance." ^ This, 

 restated in terms of protoplasmic activity, reads as follows : 

 "The early growth of the cell, the increasing bulk of 

 contained protoplasm, the accumulation of nutritive material, 

 correspond to a predominance of protoplasmic processes 

 which are constructive or anabolic. The growing dispropor- 

 tion between mass and surface must, however, imply a 

 relative decrease of anabolism. Yet the life, or general 

 metabolism, continues, and this entails a gradually increasing 

 preponderance of destructive processes or katabolism. So 

 long as growth continues the algebraic sum of the proto- 

 plasmic processes must be plus on the side of anabolism. 

 The limit of growth, when waste has overtaken and is 

 beginning to exceed the income or repair, corresponds in 

 the same way to the maximum of katabolic preponderance 

 consistent with life. The limit of growth is the end of 

 the race between anabolism and katabolism, the latter 

 being the winner.2 Again restated, but this time in terms 

 of the cell and its environment — Growth is primarily 

 dependent upon the absorptive power which the cell 



^ Geddes and Thomson, The Evolution of Sex, 

 2 Ihid, 



