A chronological account of observations on the nature of the shell membrane protein system is presented. The review indicates that although the major protein in the shell membrane is not elastin, it does contain desmosine and isodesmosine – the cross-linking amino acids. The membranes also contain small amounts of collagen. The formation of these proteins can be impaired by the inclusion of lathyrogens in the diet of laying hens. This impairment is caused by a failure to synthesize cross-links of membrane protein and this is very similar to the effect obtained when hens are fed copper-deficient diets. The disruption of the protein system has a considerable effect on the development of eggs, which are abnormal in size, shape and shell texture. The lathyrogens also have a depressing effect on egg production. The problems and prospects of utilizing seeds of certain Lathyrus plants containing lathyrogens are indicated.
