Candling During Incubation: The First Week.
	DAY 1
	From Daily Changes in the Weight and Form of the Developing Chick Cornell Bulletin 205, by Dr. A. Romanoff (1931)	image

What's Happening Now

During the first day, the germinal disc (or blastoderm) resumes activity, which means the cells will continue to grow and divide. At the beginning of the day the cells were pretty much just a single layer sitting on top of the yolk. By the end of the day, they have differentiated into three different layers: the ectoderm - which will end up as the outside of the bird; the endoderm which will become the gastrointestinal tract; and the mesoderm which becomes everything in between. The primitive streak is the structure through which cells move to get to their appropriate layers. None of this can be seen with the naked eye.

What to Look For
If the egg still looks like it did when it was fresh, don't worry. It took me years before I could recognize anything at this stage. If you *do* see something, it is likely to look like a shadow attached to the yolk, no bigger than the end of your pencil. If you compare very carefully against a fresh egg, you might see an even smaller spot on the fresh egg. ALL eggs have these whether they are fertile or not. In fertile eggs, it grows into a duckling given the right conditions. In *in* fertile eggs, it doesn't.
live developing egg	same egg as to the left, with the blastoderm marked	live developing egg	same egg as to the left, with the blastoderm marked

What to Watch Out For
Unless the egg is cracked, or smells bad, there is no need to worry about leaving eggs in the incubator. If you are not *sure* it is clear (not growing), then leave it for a few more days and check again.
	image	image	image
The dark spot in this egg is not a good sign. It might have been a blood spot that was missed when the egg was first candled. It is too soon for the germ to be this noticeable, so it can't be that.	text	text	text
Don't discard any eggs yet… wait till day 4-7

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