Austin Hughes' data: a point pattern
of displaced amacrine cells in the retina of a rabbit.
152 ``on'' cells and 142 ``off'' cells in a rectangular sampling frame.

The true dimensions of the rectangle are 1060 by 662 microns.
The coordinates here are scaled to a rectangle of height 1 and width
\(1060/662 = 1.601\) so the unit of measurement is approximately 662 microns.

The data were analysed by Diggle (1986).