Do "d-blob" and "l-blob" hypercolumns tessellate the monkey visual cortex?

The orientation selective neurons in the monkey striate cortex seem to be organized in pairs of mirror symmetrical hypercolumnar patches, each of which centered by a "cytochrome oxidase blob." A simple scheme derived from recent data of Blasdel and Salama reconciles earlier models assuming either linear or circular representation of the preferred direction of edges in the visual field.