The problem of theflow of materialsat stresses far below their normal yield‐values is discussed, and it is pointed out that the sharpness with which yield‐values can be measured depends on the grouping of the relaxation times for the different strains set up within the material, an uneven distribution making for a sharper definition. Any sharp and drastic change in the relaxation time of the system as a whole may justifiably be said to constitute a yield‐value, the question as to which of these points is actually taken astheyield‐value depending on the conditions of the experiment. These considerations are reinforced by a discussion of the results (to date) of certain experiments on flour doughs, and it is claimed that flour dough is a peculiarly suitable material for such investigations. A new rapid method for studying flow in flour doughs, recently described in the literature, is discussed. The dangers of classifying materials in hard‐and‐fast rheological divisions is emphasized, while it is pointed out that for practical purposes, and given adequate safeguards, such classifications may be extremely useful.