How Do Baby Birds Breathe Inside Their Eggs?

istock.com/aluxum
istock.com/aluxum

You might not realize it while you’re frying them sunny side up on a Sunday morning, but chicken eggs (and those of other birds, and reptiles) are some pretty sophisticated pieces of packaging.

Hard-shelled bird eggs contain albumen, or “egg white,” and a yolk. The fertilized egg cell, or embryo, develops within the yolk and feeds off of it and the white. The baby bird has shelter, food, almost everything it needs inside the egg; except, it seems, a little fresh air.

Animals that develop inside their mothers, like mammals, get their oxygen from mom through the umbilical cord. A bird in an egg doesn’t have as obvious a way to take in oxygen and get rid of carbon dioxide, but the egg, again, takes care of things.

Directly under the egg's shell are two membranes. When the eggs are laid by the mother they’re very warm, and as they cool the material inside the egg shrinks a little bit. The two membranes pull apart a little and create a small pocket or sack of air. As the developing bird grows, it breathes in oxygen from the air sack and exhales carbon dioxide. Several thousand microscopic pores all over the surface of the egg allow the CO2 to escape and fresh air to get in.

These pores also allow moisture to get into the egg to keep developing bird and the egg parts from drying out, which is why hard-boiled eggs always feel a little heavier than raw ones.

What Are the 12 Days of Christmas?

Antoninapotapenko/iStock via Getty Images
Antoninapotapenko/iStock via Getty Images

Everyone knows to expect a partridge in a pear tree from your true love on the first day of Christmas ... But when is the first day of Christmas?

You'd think that the 12 days of Christmas would lead up to the big day—that's how countdowns work, as any year-end list would illustrate—but in Western Christianity, "Christmas" actually begins on December 25 and ends on January 5. According to liturgy, the 12 days signify the time in between the birth of Christ and the night before Epiphany, which is the day the Magi visited bearing gifts. This is also called "Twelfth Night." (Epiphany is marked in most Western Christian traditions as happening on January 6, and in some countries, the 12 days begin on December 26.)

As for the ubiquitous song, it is said to be French in origin and was first printed in England in 1780. Rumors spread that it was a coded guide for Catholics who had to study their faith in secret in 16th-century England when Catholicism was against the law. According to the Christian Resource Institute, the legend is that "The 'true love' mentioned in the song is not an earthly suitor, but refers to God Himself. The 'me' who receives the presents refers to every baptized person who is part of the Christian Faith. Each of the 'days' represents some aspect of the Christian Faith that was important for children to learn."

In debunking that story, Snopes excerpted a 1998 email that lists what each object in the song supposedly symbolizes:

2 Turtle Doves = the Old and New Testaments
3 French Hens = Faith, Hope and Charity, the Theological Virtues
4 Calling Birds = the Four Gospels and/or the Four Evangelists
5 Golden Rings = the first Five Books of the Old Testament, the "Pentateuch", which gives the history of man's fall from grace.
6 Geese A-laying = the six days of creation
7 Swans A-swimming = the seven gifts of the Holy Spirit, the seven sacraments
8 Maids A-milking = the eight beatitudes
9 Ladies Dancing = the nine Fruits of the Holy Spirit
10 Lords A-leaping = the ten commandments
11 Pipers Piping = the eleven faithful apostles
12 Drummers Drumming = the twelve points of doctrine in the Apostle's Creed

There is pretty much no historical evidence pointing to the song's secret history, although the arguments for the legend are compelling. In all likelihood, the song's "code" was invented retroactively.

Hidden meaning or not, one thing is definitely certain: You have "The Twelve Days of Christmas" stuck in your head right now.

What Are the 12 Days of Christmas?

Tevarak/iStock via Getty Images
Tevarak/iStock via Getty Images

Everyone knows to expect a partridge in a pear tree from your true love on the first day of Christmas ... But when is the first day of Christmas?

You'd think that the 12 days of Christmas would lead up to the big day—that's how countdowns work, as any year-end list would illustrate—but in Western Christianity, "Christmas" actually begins on December 25th and ends on January 5th. According to liturgy, the 12 days signify the time in between the birth of Christ and the night before Epiphany, which is the day the Magi visited bearing gifts. This is also called "Twelfth Night." (Epiphany is marked in most Western Christian traditions as happening on January 6th, and in some countries, the 12 days begin on December 26th.)

As for the ubiquitous song, it is said to be French in origin and was first printed in England in 1780. Rumors spread that it was a coded guide for Catholics who had to study their faith in secret in 16th-century England when Catholicism was against the law. According to the Christian Resource Institute, the legend is that "The 'true love' mentioned in the song is not an earthly suitor, but refers to God Himself. The 'me' who receives the presents refers to every baptized person who is part of the Christian Faith. Each of the 'days' represents some aspect of the Christian Faith that was important for children to learn."

In debunking that story, Snopes excerpted a 1998 email that lists what each object in the song supposedly symbolizes:

2 Turtle Doves = the Old and New Testaments
3 French Hens = Faith, Hope and Charity, the Theological Virtues
4 Calling Birds = the Four Gospels and/or the Four Evangelists
5 Golden Rings = the first Five Books of the Old Testament, the "Pentateuch", which gives the history of man's fall from grace.
6 Geese A-laying = the six days of creation
7 Swans A-swimming = the seven gifts of the Holy Spirit, the seven sacraments
8 Maids A-milking = the eight beatitudes
9 Ladies Dancing = the nine Fruits of the Holy Spirit
10 Lords A-leaping = the ten commandments
11 Pipers Piping = the eleven faithful apostles
12 Drummers Drumming = the twelve points of doctrine in the Apostle's Creed

There is pretty much no historical evidence pointing to the song's secret history, although the arguments for the legend are compelling. In all likelihood, the song's "code" was invented retroactively.

Hidden meaning or not, one thing is definitely certain: You have "The Twelve Days of Christmas" stuck in your head right now.

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