PRINCIPLES OF BIOLOGY. 
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supply of assimilable matter, but each variety of food must be 
present, since, e.<j., an absence of lime would dwarf the 
skeleton ; while the fact that the machinery of absorption is 
limited in surface and power, would of itself check the growth 
of an Oliver Twist, even though Mr. Squeer’s treacle and 
philanthropy were as inexhaustible as the cruse of oil, or, 
better still, as the National Debt. 
But the increments called growth at last absolutely 
cease. The same food which is used up as force cannot 
be used to increase bulk, and since it is a mechanical axiom 
that the strain incurred in the movement of a large bulk is 
proportionately greater than the strain incidental to that for 
a small bulk, it follows that a time must come when the 
whole of the food will be used up in the production of force. 
If the Claimant, who is shortly to make his exit from prison, 
weighs twenty-five stone—while a child weighs five—the force 
which the ex-convict must exert to walk away from the doors 
is not five times the exertion of the child in covering the 
same distance, but a great deal more than five times. The 
bulk of the food which he has eaten will be required for 
locomotive purposes, a proportion will go to replace waste, 
and none will be left for addition. Long ago, if plethora be 
not an exception to Mr. Spencer’s rule, the Claimant reached 
the “ state of moving equilibrium.” Then there are minor 
considerations. No little energy is used up in the transport of 
material from the absorbing surface to the periphery of 
Mr. Orton’s person, though, on the other hand, it has to be 
conceded that Mr. Orton’s person, being of considerable bulk, 
would lose and consequently have to brew heat (a fancy 
energy ) less rapidly than when he was young and innocent. 
Applying the general principle to less noteworthy instances, 
we shall expect to find some complications. Plants have 
scarcely any limit of growth, and this may be due to the fact 
that they have not to expend force. The pike and the 
crocodile, which are alleged to grow as long as they live, 
may do so because their mode of life requires little display of 
energy, and the former lives in a medium of the same density 
as its body—in a condition, in fact, of perpetual sofa. 
Variations must, of course, be expected in the 
application of this theory, different species having such very 
different modes of feeding, digesting, and behaving. The 
rule will apply best of all to individuals of the same species. 
As has been said, the ultimate size largely depends 
on the initial bulk with which a creature starts. Of two men, 
one a manufacturer and the other a street vendor, given equal 
quantities of shrewdness; the manufacturer makes the larger 
