Also, on some wing surfaces,
local damage to the epidermis can mimic the focal signal,
inducing the formation of an ectopic eyespot (Fig. 3A,iv).(31,32,34)
Nijhout(29) suggested that the eyespot focus may act as a
local source that generates a conical morphogen gradient
extending over the surrounding epidermis, with different
concentrations specifying concentric rings within which the
scale cells later synthesise different pigments. In grafting
experiments using foci taken from the anterior (small) or
posterior (large) eyespot in B. anynana, the size of the
induced eyespot depends on the origin of the focus