Five years have elapsed since the last installment of my notes on observed growth of my left thumbnail, and more than 25 years since these monthly observations began.1 On the first day of each month, I made a mark with a small file at the point where the nail emerges below the cuticle. With the passage of time, the mark moved slowly to the free edge of the nail. The end of the growth period was taken as the day the scored mark reached the edge of the underlying matrix. The length of the nail measured on my left thumb has remained fixed as 1.45 cm. A small tattoo mark put a short way from the edge of the cuticle provides another point of reference. With this system, the larger the number of days needed to traverse the distance, the slower the growth. In the Figure and Table, the
Bean WB. Nail Growth: Twenty-five Years' Observation. Arch Intern Med. 1968;122(4):359–361. doi:10.1001/archinte.1968.00300090069016
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