rence between the movement of food prices and other prices.

3.--Changes in the general level of prices must have prior causes, but
they, themselves in turn cause economic disturbance. They give a tilt to
the whole industrial system which manifests itself in the outcome of
distribution. The effects upon the distribution of the product of an
upward movement of prices are ordinarily different from those produced
by a general decline in prices.

It is well to begin with the first case--a period of a rise in the
general price level. To give an accurate analysis of the successive
interactions by which an upward movement in the general price level,
once stimulated, asserts itself, is both a delicate and lengthy task. It
cannot be attempted here.[40] It suffices to note the ordinary
distributive results of the process; with the important reservation,
however, that they do not occur in the measure that the rise is
occasioned by a general reduction in the productivity of industry such
as might be caused by war.

There are firstly what may be called the direct results. Prime costs of
production do not increase as rapidly as prices, and supplementary costs
rise even less rapidly than prime costs. Prices rise faster than wages
and interest charges, and rents tend to remain fixed by leases and other
arrangements. Especially in the first year or two of rising prices, the
rise in wages tends to be slow; in the later stages it ordinarily
becomes more rapid.[41] Thus Mitchell in his study of wage and price
movements during the Greenback Period in the United States (1860-80)
writes that "... The table shows an almost universal rise of wages
during the war--though a rise far from equal to the advance of wholesale
or retail price."[42] And in his study of price and wage movements from
1890-1910 in the United States he writes, "The figures indicate that the
prices of labor are influenced by changes in business conditions, but in
less measure than the price of commodities, even at retail. The general
average declines after the panic of 1893, recovers in 1896, advances in
1898-1903, makes very little gain in the dull year of 1904, and then
rises rapidly again in 1904-7. But the degree of rise and fall is
considerably less than that of commodities at wholesale and just about
the same as that of food at retail."[43]

The lag of wages behind prices varies in degree in different industries
and occupations, for neither prices nor wages go up