Mammalian development pigmentation

In 1885, Ehrlich showed that animals after injection of a mixture of p-phenylenediamine and a-naphthol, developed a blue colour in their tissues, owing to formation of an indophenol pigment. Batelli and Stern, in 1912, found that this property was common to almost all mammalian tissue, and ascribed it to the presence of an enzyme, indophenol oxidase. Keilin, in 1929, discovered the significance of the enzyme when he showed that it was able to re-oxidise cytochrome, and hence forms part of an important oxidation system in the living cell. 

---