Statistics of Structure of the Cell Walls of Micrococcus lysodeikticus. III. Isolation of a New Peptide Dimer, Nα-[L-Alanyl-γ-(α-D-glutamyl-glycine )]-L-lysyl-D-alanyl-Nα- [L-alanyl-γ-(α-D-glutamyl-glycine)]-L-lysyl-D-alanine