If we could open the egg today and take a look inside (which we can't, of course!) we'd see the chick at this stage of incubation looks a bit like a tiny alien. The eyes and the beak would be immediately obvious - they both look much too big for the body.
Have you ever wondered when chicks start to develop proper wings? One of the most surprising things about today is that the flight feathers on the wings start to develop.
As a result of these feather tracts already being developed when the chick hatches, chicks will show wing feather growth amazingly early after hatching.
One of my 4 day old Wyandotte chicks - with flight feathers.
Much of the facial development from yesterday continues into today. The eyelids in particular enlarge and the lower one grows upwards; the nose opening is growing and narrowing and the beak continues to harden.
The incubated egg at day 10.
Elsewhere on the body the ridge where the comb will be is forming and the toes, which are now separate, begin to grow claws at the end.
The chorioallantoic membrane, which was 80% closed yesterday, is complete today and now surrounds the yolk, allowing oxygen to be brought to the embryo and carbon dioxide and urine to be taken away.
Again today you may be able to see, especially in light-coloured eggs, the chick moving about. Its heartbeat is around
It's becoming more and more difficult to see exactly what's going on in darker coloured eggs because the embryo is growing very quickly and beginning to fill the space where once we could identify blood vessels.
In some eggs it's not as clear. Even with the colour and saturation levels altered on the photograph it's still not possible to see much, although the blood vessels and the embryo are clearer.
Today is another candling stage, in particular for any eggs you candled at day 7 which seemed to be showing no signs of development.
By today signs of development, if they're going to show, should be quite clear, even if you can't see much detail.
Certainly candle those eggs you marked as questionable and, if you want to check others for continuing growth, that's fine. Make sure you mark the air cell again so that it's clear it's growing. The air cell markings will also become important as we get close to hatching.
If you've never candled before and want to know how, take a look at this page before you go any further. It will open in a separate window so you can return here to know what you're looking for when you do candle.
As the eggs get further into incubation they become more porous, allowing the blood system to take in oxygen.
For that reason it's really very important that, if you candle, you make sure everything - including your hands - is spotlessly clean.
If you neglect cleanliness and bacteria enter the eggs, it will be disastrous for your hatch levels. In a warm, moist environment like an incubator bacteria multiply very quickly and eggs will become bad, potentially exploding and releasing bacteria into all the other eggs in the incubator.
I've just candled my eggs again and there are some which look as though they're not developing. Should I discard them now?
This is a personal decision. I tend to discard white eggs, into which I can clearly see, at this point if there's no signs of growth but I don't take out eggs which are more difficult to candle before day 14 - and really dark, hard to candle eggs like the chocolate brown Marans I often leave in until the end, just to be sure.
If the egg is showing no signs of development by now, the chances are it's not going to develop - although you just never know!
Unless it's smelling bad or it's cracked and / or oozing liquid, there's no harm in leaving it in the incubator for a couple more days.
On the right is an egg which I candled at day 7 and saw no development whatever - you can see the 'X' mark at the top which is my shorthand for 'no signs of anything'.
But I candled again at day 12 (this pic) and there was clearly an embryo in there. See the dark spot which is the chick's eye, and the developing blood supply?
So as I say - it's up to you.
Personally, if I have an egg which I'm unsure about at day 10 I would mark it in some way and candle again at day 14. If there is still no sign then - discard.
On each day of this incubation series I feature a photo of one of my own chicks.
It helps us keep our minds focused on what we're working towards - a healthy, happy chicken.
These are two of my favourite chickens. The larger one is a three day old Light Sussex, and the one trying to burrow underneath is the same age Lemon Millefleur Sablepoot. As you can see, they're the best of friends!
Just click on any of the pictures below to go to that page. The day 7 page is there in case you missed out candling eggs earlier in the process.
Have you joined my incubating and hatching group yet?
If you're having a go at hatching your own eggs and it's new to you, you might want to consider joining my free 28-day series called "Hatching Happy Chickens".
You'll have e-mails personally delivered every day describing that day's developments in the incubation process, and pointing out as this page does exactly what you need to be doing.
It's free, and it's fun! Don't miss out - click on the pic to have a look at more information about exactly what you'll get.
The easiest way to follow my hatching series is to sign up for the e-mails. However, if you'd rather not do that, these are links you need to work logically through the series.
Important: copyright warning.
'The Incubated Egg' image is a commissioned artist's impression and, like all images on this site, is subject to copyright under the Copyright Law of the United States of America 1976.
Under no circumstances is permission granted to copy or otherwise use this image.
All other images of candling on this and other pages are my own and are not to be used without permission.
If you wish to use these or any other images on this site for educational purposes you are required to contact me by using the form to be found on this page.
For my full copyright policy see this page.