Creatin — Chambers's Encyclopaedia

Creatin, or KREATIN (Gr. kreas, 'flesh'), a constant and characteristic constituent of the striped muscle of vertebrates. It was discovered by Chevreul in 1835, but little was known about it till Liebig published his researches on the Chemistry of Food in 1847. Its chemical formula is $\text{C}_4\text{H}_5\text{N}_3\text{O}_2$ . Except in one doubtful case, it has always been found as above indicated; it is very uncertain if it ever occurs in unstriped muscles, and it has never been demonstrated in invertebrates. A dehydrated form, known as Creatinin, $\text{C}_4\text{H}_7\text{N}_3\text{O}$ , occurs as a constant constituent of urine, and has also been demonstrated in fish muscles. Under the influence of acids, creatin becomes creatinin, and by hydration the transformation may be reversed. As these changes may readily occur during extraction, there is often doubt whether creatin or creatinin is present in a given case. See Appendix to Foster's Physiology; Krukenberg, Unters. Physiol. Inst. (vols. iii.-iv. 1880-81).