Thank you, everyone. We had her necropsied at our state lab in Virginia. She had a severe fungal infection--aspergilliosis (sp?). Apparently, it's a fungus both people and birds carry in their system, but the vet who examined her body said that something else would have been stressing her for the infection to take hold. She told us that once this fungus gets going, there's really nothing you can do. She also told us that the bird had not aspirated, which was what we were worried about--we thought that giving her some of the liquid by dropper that maybe we'd compromised her, but that wasn't the case. Still doesn't bring her back, but at least we know we didn't cause it. So, we are going to boost the probiotics and the protein in our other pullets after determining that maybe they are a bit underweight. Here we were worried about them getting too big too fast with all the debate about when to switch to layer food, and it turns out they might actually be underweight. She said if we could pinch the keel, they were too thin. We're first timers so we were surprised since they have access to all the food they want and since they otherwise look so healthy. Anyhow, we are learning a lot. But it's still so hard to look out at them and keep wondering where the 6th bird is. She was both my and my husband's favorite. *sigh* Didn't think I'd get so attached in just 2 months! Oh well, reading this board it's obvious I'm not alone in that regard!