Few kinds o of labor develop the body in a sym­metrical manner. This is true even in an elementary division of labor. The carpenter and the blacksmith usually have strong large shoulders and arms but small and weak legs. The farmer from excessive ben­ding over his work loses in a greater or less deg­ree his elasticity of body and often becomes sto­op-shouldered. If such defects result from the more primitive forms of labor it is not at all strange that the laborers of the modern industrial world show bodily peculiarities and variations that correspond in a marked degree to their respective trades.