neral rate of
wages rests.

Thirdly, there is the fact that certain forms of work on which youthful
labor is employed, give no preparation and training for the further
stages of life and work; and these blind alley employments are filled by
children born in the lowest industrial groups.

Then there are the barriers of different kinds to free movement
throughout all parts of the field of employment. There are the barriers
of sex which have added to the crowding of certain occupations and
industrial grades. There are the barriers of race and religion, which
have affected the flow of labor between different industries. Lastly,
there is the barrier of color, which has prevented the negroes from
developing their natural ability. These barriers may be well justified,
in part or in whole, by other considerations. That question need not be
considered here. But they certainly contribute to the formation of
relatively separate groups of wage earners, with different levels of
earnings.

4.--The existence and activities of labor unions are still another
factor in the formation of relatively separate groups. In many cases
labor organization tends to follow closely the lines of separation or
unity established by the other causes of group separation or unity.
There is often a tendency for a single union to include within its
limits the whole of a group within which all the conditions underlying
the idea of a general rate of wages are well fulfilled; or for various
unions to merge or act together, if these conditions are well fulfilled
between them. G. D. H. Cole has given a case in point. "Clearly the ease
with which an industrial union can come into being depends upon the
sharpness of the distinction between the skilled and unskilled in the
industry concerned. Thus in the mining and textile industries, as we
have already noted, there is no very sharp distinction between the two
classes of workers. In mining, the boy who enters the pit has every
chance of passing before many years have gone by into the ranks of the
coal getters, who form the skilled section of the mining community.
There is no sharp division or cleavage of interest between the main
sections of the mining community. Promotion runs easily from one grade
to another, and therefore, it is easier to realize a form of combination
in which all the various sections are grouped together in a single
industrial organization."[33]...

This tendency, however, has not been pe