The distribution and carbohydrate composition of the organic matrix in hen egg shell

After the removal of membranes and cuticle, successive arbitrary layers were dissolved with dilute HC1 from shells laid by a single Thornber “ 404 “ hen. The rate of solution was inversely related to the nitrogen content at a given level but, for a given nitrogen content, was faster from the inside of the shell than from the outside. Matrix is distributed unevenly through the mineralised shell, the concentration of nitrogen and carbohydrates increasing to a maximum about two‐thirds of the way through the shell from the inside. With the exception of hexose, these concentrations then decrease to values as low, or lower than those found on the inside of the shell. The content of chondroitin sulphates in the matrix is fairly constant while that of sialic acid decreases from the inside to the outside. Non‐chondroitin sulphate polysaccharides are more highly concentrated in matrix in the inner and outer strata of the shell than in the region of maximum matrix concentration. Aspects of shell composition and calcification are discussed in relation to these results.