. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. STIMULATION OF CHROMATOPHORAL NERVE-FIBERS In Fundnlus the cutting- of the chromatophoral nerve-fibers stimu- lates the dispersion of melanophore pigment, not its concentration. Electrical stimulation of these fibers, on the other hand, stimulates con- centration, not dispersion (Mills, 1932). In my opinion these condi- tions are not the result of an exclusive action of the two means of stimulation on different classes of fibers. Both concentrating fibers and dispersing fibers are in all probability excited by each agent. Th
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. STIMULATION OF CHROMATOPHORAL NERVE-FIBERS In Fundnlus the cutting- of the chromatophoral nerve-fibers stimu- lates the dispersion of melanophore pigment, not its concentration. Electrical stimulation of these fibers, on the other hand, stimulates con- centration, not dispersion (Mills, 1932). In my opinion these condi- tions are not the result of an exclusive action of the two means of stimulation on different classes of fibers. Both concentrating fibers and dispersing fibers are in all probability excited by each agent. The difference is due, I believe, to the greater ease with which concentrating fibers can be excited electrically and dispersing fibers by cutting. In the dogfish, where only one set of fibers is present, those concerned with pigment concentration, both types of stimulation are effective in bring- ing about the same reaction. These reactions are best seen in dog- fishes that have not reached the stage of maximum darkness but which are only moderately dark. This is probably due to the great effective- ness of the pituitary secretion by which the dogfish melanophores are excited to disperse their pigment as contrasted with the weaker effect of the concentrating nerve-fibers which induce the opposite change (Parker and Porter, 1934). CONCLUSION The concentrating melanophore nerve-fibers of the dogfish can be excited to action whereby the fish may be locally blanched as wrell through electric stimulation as through mechanical stimulation (cutting). REFERENCES LUNDSTROM, H. M., AND P. BARD, 1932. Hypophysial Control of Cutaneous Pig- mentation in an Elasmobranch Fish. Biol. Bull., 62: 1. MILLS, S. M., 1932. The Double Innervation of Fish Melanophores. Jour. pcr. Zool, 64: 231. PARKER, G. H., AND H. PORTER, 1934. The Control of the Dermal Melanophores in Elasmobranch Fishes. Biol. Bull., 66: Please note that these images are extracted from scanned page images that may have b
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