PURPOSE: To enable the exclusion of an inhibitory factor of natural protective mechanism by injecting microorganisms into the content of an egg enclosed in egg shell and culturing and proliferating the inoculated microorganisms.

CONSTITUTION: Laid egg with shell is put into a vessel maintained at about 30°C. CO2 gas and water in the egg are removed by evacuating the system to an extent not to break the egg shell. Microorganisms are injected into the egg and the inoculated microorganisms are cultivated to exclude the inhibitory factor of the proliferation of the microorganisms and to promote the proliferation.