A study of the progressive deposition of shell in the shell gland of the domestic hen

Synopsis

It is known that the organic matrix of the shell is not distributed evenly throughout the calcified portion and an experiment has been described in which incompletely shelled eggs were removed from a group of domestic hens after being in the shell gland for various known periods.

Rate of shell deposition and the timing of the deposition of the various layers in the shell has thus been determined, and it was found that shell deposition was initially slow for the first 3 h in the gland and thereafter more rapid, at a constant rate of 322 mg h⁻¹, until termination after 17 or 18 h. The narrow layer low in matrix at the top of the mammillary layer of the shell was laid down during the 7th to 9th hour in the gland and did not appear to be associated with any change in shell deposition rate. It was also found that the characteristic pole to pole thickness patterns of shells were present at the earliest measurable stage, that is after about 8 h in the gland.