An emitting device in an organic electroluminescent device is disclosed, in which a lower electrode pattern is formed on a substrate, an emitting layer pattern is formed on the lower electrode pattern, and a transparent electrode is formed on the emitting layer pattern and an emitting body having a structure in which an organic thin film emits light when an application current is applied to it. There are a plurality of gauge blocks of different sizes and shapes for determining the vertebral space for subsequent insertion of a permanent artificial spinal disc. The present invention also relates to a method of repeated cycles of mutagenesis, shuffling and selection which allow for the directed molecular evolution in vitro or in vivo of proteins.