ADAPTATION. 239 



considerable extension of the iron manufacture, when it at 

 length takes place, will cause but a comparatively small 

 additional demand on the coal-owners and coal-miners — a 

 demand which will not, for a long period, suffice to cause 

 enlargement of the coal-trade, by drawing capital and labour 

 from other investments and occupations. And until the per- 

 manent extra demand for coal has become great enough to 

 draw from other investments and occupations sufficient 

 capital and labour to sink new mines, the increasing produc- 

 tion of iron must be restricted by the scarcity of coal, and 

 the multiplication of ship-yards and ship-builders must be 

 checked by the want of iron. Thus, in a community which 

 has reached a state of moving equilibrium, though any one 

 industry directly affected by an additional demand may 

 rapidly undergo a small extra growth, yet a growth beyond 

 this, requiring as it does the building-up of subservient in- 

 dustries, less directly and strongly affected, as well as the 

 partial imbuilding of other industries, can take place only 

 with comparative slowness. And a still further growth, re- 

 quiring structural modifications of industries still more dis- 

 tantly affected, must take place still more slowly. 



On returning from this analogy, we see more clearly the 

 truth that any considerable member of an animal organism, 

 cannot be greatly enlarged without some general reorganiza- 

 tion. Besides a building up of the primary, secondary, and 

 tertiary groups of the subservient parts, there must be an un- 

 building of sundry non-subservient parts; or, at any rate, 

 there must be permanently established a lower nutrition of 

 such non-subservient parts. For it must be remembered that 

 in a mature animal, or one which has reached" a balance 

 between assimilation and expenditure, there cannot (suppos- 

 ing general conditions to remain constant) be an increase in 

 the nutrition of some organs without a decrease in the nutri- 

 tion of others; and an organic establishment of the increase 

 implies an organic establishment of the decrease — implies 

 more or less change in the processes and structures through- 



