I have some eggs in the incubator leftover from a broody hen who hatched out Monday. She went broody while I was on vacation and I am not sure of the time table on the leftovers eggs. All but two hatched last night and this morning. So tonight with no signs, I decided to candle the last two before the big "discard". Well as I was balancing egg and light, I dropped one of the eggs. Half the shell came off. The sac is intact. I now see the chick moving around in the sac. I feel lower than a slug... I can't discard it. I'm afraid to break the sac. There is no way to "repair" that much shell. I'm worried that the sac will dry out around him. I increased the humidity. I'm hoping it is far enough developed that it will just break the sac itself and "hatch". Fingers crossed I didn't just doom a little peep I was trying to save. Sharing my uncertainties and regrets... 
