. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATION PROXIMAL RETINAL PIGMENT 175 these cases distal migration had proceeded to completion. Hydrogen ion concentration, within the experimental range produced by the addition of carbon dioxide, did not affect appreciably the position of the pigment. DISCUSSION It should be noted that the animals were neither dead nor even completely quiescent at the end of maximum exposures to carbon dioxide, nitrogen, or acidified water. In all cases the swimmerets were moving and in many cases the mouth-parts and other appendages as w
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATION PROXIMAL RETINAL PIGMENT 175 these cases distal migration had proceeded to completion. Hydrogen ion concentration, within the experimental range produced by the addition of carbon dioxide, did not affect appreciably the position of the pigment. DISCUSSION It should be noted that the animals were neither dead nor even completely quiescent at the end of maximum exposures to carbon dioxide, nitrogen, or acidified water. In all cases the swimmerets were moving and in many cases the mouth-parts and other appendages as well. Check experiments showed that these animals could stand the most unfavorable conditions to which they were subjected in the experiments described in this paper, and would recover when replaced in running water. The only one of the three factors tested which showed any con- sistent relation to migration of the proximal retinal pigment was oxygen content. As this decreased, the pigment began to move toward the distal position, even in darkness, and this migration was invariably completed when the oxygen tension had dropped to zero. If we are correct in supposing that in aquatic Crustacea there is a fair degree of correlation between the oxygen content of the water and the metabolic activity of the animal (as expressed by its oxygen con- sumption) it seems reasonable to believe that the pigmentary changes here observed are associated in some way with varying metabolic conditions. Evidence that the supposition is correct is afforded by Amberson, Mayerson, and Scott (1925). In a large number of experiments on the lobster (Homarus) they found a correlation between oxygen tension in the water and oxygen consumption by the animal so close as to warrant the statement that "at every instant the oxygen-consumption is directly proportional to the oxygen-tension in the sea-water at that instant" (1925, p. 175). They found an equally close correlation of the same sort in the p
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
