"The banded or laminated structure in the Paleozoic schists of the South island, New Zealand, is shown to be a pseudo-stratification. The conclusion is reached that this banded structure is mainly the result of metamorphic differentiation, brought about by chemical mobilization of the more readily soluble constituents of the rock. In accordance with the theory of Sander, it is suggested that chemical mobilization reaches its maximum when mechanical action has reduced the grain size of the original rock so much that the velocity of the direct componental movement of grains, which is directly proportional to the grain size, is below a critical value. Supplemental influence of magmatically derived material, especially silica, is admitted but is considered subordinate. In many places the laminated structure of metamorphic origin has been transposed and partly obliterated as strong deformation continued."