A McGill University chemist named Joe Schwarz is a local celebrity in these parts, tirelessly and effectively promoting the popularization of science through magic shows, lectures, and entertaining columns in the Montreal Gazette. As far as I know, he has never disparaged psychology as a science. He recently discussed the work of John Dalton in one of his columns and (because it is such a rare event) I was delighted to discover that, for once, his comments needed a bit of correction. I've submitted the following as a letter-to-the-editor along with a cover letter which predicted that he would "take the correction in good (not vitreous) humour". I thought TIPsters teaching colour vision might find the story of interest as well. -Stephen ---------------------------------------------------------------- In a recent column (April 25, 1999), Joe Schwarcz discussed the work of the great chemist John Dalton and Dalton's astute observations on his own colour blindness. Although I enjoyed Dr. Schwarcz's account, it is inaccurate in a few respects, and the story of Dalton's eyes has a remarkable conclusion of which Dr. Schwarcz is unaware. First, Dalton did not suffer from protanopia but from the other form of red-green colour blindness, deuteranopia. Second, rather than Dalton being "unable to come up with any explanation" of his colour-blindness, he had a definite theory, and it was in order to prove his hypothesis that he donated his eyes to science. His theory was that the jelly-like interior of his eyes (the vitreous humour) was tinted blue, and therefore absorbed the long wavelengths of red light before they could reach the visual receptors. The autopsy proved his hypothesis false, as his vitreous humour was found to be absolutely clear. Third, the eyes were not lost during World War II, and this led to the remarkable conclusion of this story. A few years ago David Hunt and his colleagues at the University of London were allowed to take small samples from Dalton's preserved eyes and subjected them to DNA analysis. This demonstrated 150 years after Dalton's death that one of his genes for colour vision was indeed missing. The photopigment it encoded is responsible for sensing light in the middle wavelength range; hence Dalton was a deuteranope, contrary to what had been previously believed. The work is published as: Hunt, D., Dulai, K., Bowmaker, J., & Mollon, J. (1995). The chemistry of John Dalton's color blindness. Science, 267, 984-988. -------------------------------------------------------------------- ------------------------------------------------------------------------ Stephen Black, Ph.D. tel: (819) 822-9600 ext 2470 Department of Psychology fax: (819) 822-9661 Bishop's University e-mail: [EMAIL PROTECTED] Lennoxville, QC J1M 1Z7 Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy ------------------------------------------------------------------------
