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Journal of Experimental Biology 16,524-529 (1939)
Published by Company of Biologists 1939

Photomechanical Changes in the Pineal of Lampreys

F. G. W. KNOWLES B.A., D.PHIL.¹

¹ Department of Zoology and Comparative Anatomy, Oxford, and Marlborough College, Wilts

1. The pigment present in the pineals of ammocoete larvae is a reflecting pigment. There are indications from its solubilities that this pigment is guanin.

2. No differences in the distribution of this pineal pigment can be seen in animals kept under various conditions of illumination, or when examined soon after transference from light to darkness.

3. The position of the nuclei in the pineal retinal cells changes under different conditions of illumination. They are diffusely scattered in the retinal region of the pineals of animals kept in the dark for seven days, but in animals kept in moderate illumination, the nuclei take up the same position in each retinal cell, thus presenting the appearance of a line of nuclei when viewed laterally. Strong illumination further accentuates this linear distribution of the nuclei.

4. These changes further substantiate the view that the pineals of ammocoete larvae are sensitive to changes of illumination.