STUDIES ON THE GROWTH OF INTEGUMENTARY PIGMENT IN THE LOWER VERTEBRATES

I. THE ORIGIN OF ARTIFICIALLY DEVELOPED MELANOPHORES ON THE NORMALLY UNPIGMENTED VENTRAL SURFACE OF THE SUMMER FLOUNDER (PARALICHTHYS DENTATUS)

¹ From the Department of Anatomy, the Ohio State University, and the Woods Hole Oceanographic Institution, Woods Hole, Mass.

Melanophores differentiate on the normally non-melaninated ventral surface of summer flounders when two conditions are satisfied. (1) The surface must be exposed to some light source when (2) the animal is in a physiological condition favoring darkening as witnessed by the behavior of the dorsal melanophores.

The melanophores develop "in situ" from potential melanophores (melanoblasts) whose presence is evidenced by the positive "Dopa" reaction, by direct observations of various stages of differentiation using direct and reflected light, by studies on regenerating scales, and by additional physiological data.

Theoretical considerations of the possible reactions involved in the experimental development of ventral melanophores and speculations as to why they are normally absent from the ventral surface are presented.