Abstract: The invention relates to a system applicable to an installation for candling eggs, to determine the presence of fertilized eggs in the cells of the egg crate grid moving on a conveyor. Row by row, the analyzing device synchronously monitors the light emission on the eggs of the row and detection of the attenuated light of emerging beams. The monitoring includes at least two close cycles of light emission. During the first cycle, which is of short duration to avoid causing glare of the detectors of the detecting device, the coordinates of possible empty cells in a row are determined and stored. During the second cycle, which is of longer duration, the coordinates of fertilized eggs of the row are determined and stored. The egg candling installation advantageously also marks the eggs, depending in particular on whether they are fertilized or not.