is a necessary accompaniment of further differentiation of
functions in the individual body or in the body-politic. As fast as each
organ of a living animal becomes confined to a special action, it must
become dependent on the rest for those materials which its position and
duty do not permit it to obtain for itself; in the same way that, as
fast as each particular class of a community becomes exclusively
occupied in producing its own commodity, it must become dependent on
the rest for the other commodities it needs. And, simultaneously, a more
perfectly-elaborated blood will result from a highly specialized group
of nutritive organs, severally adapted to prepare its different
elements; in the same way that the stream of commodities circulating
throughout a society, will be of superior quality in proportion to the
greater division of labour among the workers. Observe, also, that in
either case the circulating mass of nutritive materials, besides coming
gradually to consist of better ingredients, also grows more complex. An
increase in the number of the unlike organs which add to the blood their
waste matters, and demand from it the different materials they severally
need, implies a blood more heterogeneous in composition--an _a priori_
conclusion which, according to Dr. Williams, is inductively confirmed by
examination of the blood throughout the various grades of the animal
kingdom. And similarly, it is manifest that as fast as the division of
labour among the classes of a community becomes greater, there must be
an increasing heterogeneity in the currents of merchandize flowing
throughout that community.

The circulating mass of nutritive materials in individual organisms and
in social organisms, becoming at once better in the quality of its
ingredients and more heterogeneous in composition, as the type of
structure becomes higher, eventually has added to it in both cases
another element, which is not itself nutritive but facilitates the
processes of nutrition. We refer, in the case of the individual
organism, to the blood-discs; and in the case of the social organism, to
money. This analogy has been observed by Liebig, who in his _Familiar
Letters on Chemistry_ says:--

"Silver and gold have to perform in the organism of the state, the
same function as the blood-corpuscles in the human organism. As
these round discs, without themselves taking an immediate share in
the nutritive process, are the