THE PRINCIPLES OF BIOLOGY. 
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The restoration of lost or injured parts is another kind of 
repair ; it is greatest in the lowest organizations and least in 
the highest, from the Hydrozoa, in which the smaller part will 
produce the greater, to birds and mammals, in which wounds 
only can be healed. There is complete harmony between the 
first of the above inductions and deduction from “ First 
Principles,” viz., “that whatever amount of power an 
organism expends in any shape is the correlate and equivalent 
of a power that was taken into it from without.” The power 
required to raise the elements of the complex atoms (of food) 
to a state of unstable equilibrium is given out in their 
falls to a state of stable equilibrium, and “ the loss of these 
complex unstable substances is proportionate to the quantity 
of expended force.” A like relation may be deductively 
inferred between the activity and waste of special parts. 
The deductive interpretation of Repair, though less easy, 
appears to be in harmony with First Principles ; it would be 
simple if the blood contained (which it does only in part) 
units like those of each organ. The true explanation seems 
to be, that compound units possess the power of moulding 
adjacent fit materials into units of their own form. This 
power is called Katalytic Action. 
The repair of wasted tissue may be considered due to 
forces analogous to those by which a crystal reproduces its 
lost apex in a solution like that from which it was formed, 
which forces are called “Polarity”; and the repair of lost 
parts is caused by similar actions, the aggregate forces of 
an organism controlling the formative process going on in 
each part. 
The form of each organism seems due to some peculiarity 
in the constitution of its units, and living particles have an 
innate tendency to arrange themselves into the shape of the 
organism to which they belong. 
What, then, are these Organic Units? Not chemical 
Units ; for if so, as millions of plants and animals are mainly 
built up of such complex atoms, there would be nothing to 
account for unlike forms. Neither are they Morphological 
Units, which are cells, for some creatures (as the Rliizopod) 
do not consist of cells; the formation of cells themselves is 
to some extent only a manifestation of this same peculiar 
power. We must, therefore, conceive this Organic Polarity as 
possessed by certain intermediate units, which may be called 
Physiological Units, and must suppose that Chemical units 
combine into these infinitely more complex Units which in 
each Organism have distinctive characters. 
