Limulus Lateral Eye: Properties of Receptor Units in the Unexcised Eye

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Science  03 Dec 1971:
Vol. 174, Issue 4013, pp. 1027-1029
DOI: 10.1126/science.174.4013.1027


Single receptor units in the compound eye of the horseshoe crab were illuminated, and their impulse discharges were recorded without removing the eye from the animal. The receptors were spontaneously active in darkness and responded without saturation over a light intensity range of 1010 to 1. When the eye was excised, the receptors did not discharge in darkness and had an intensity range of 105 to 1, as is usually found. Experiments show that these and other differences result from cutting off the blood supply to the eye when it is excised. In addition, the range and shape of the intensity characteristic suggest that more than one receptor mechanism encodes light intensity in this eye.