Changes

*As the embryo grows within the egg, the composition of the egg changes.

*As the embryo grows within the egg, the composition of the egg changes.

* Both [[Exotics_-_Composition_of_the_Egg_- Anatomy & Physiology#Yolk|yolk]] and albumin diminish.

* Both [[Egg Composition and Formation - Anatomy & Physiology#Yolk|yolk]] and albumin diminish.

** [[Exotics_-_Composition_of_the_Egg_- Anatomy & Physiology#Yolk|Yolk]] providing energy for growth and maintenance of the embryo.

** Yolk providing energy for growth and maintenance of the embryo.

** Albumin providing protein for the embryo and giving up water, which is lost through pores in the [[Exotics_-_Composition_of_the_Egg_- Anatomy & Physiology#Shell|shell]].

** Albumin providing protein for the embryo and giving up water, which is lost through pores in the [[Egg Composition and Formation - Anatomy & Physiology#Shell|shell]].

* Water is produced when yolk fat is oxidised.

* Water is produced when yolk fat is oxidised.

* Water lost from the egg is replaced by air, creating the 'air cell' at the blunt end of the egg.

* Water lost from the egg is replaced by air, creating the 'air cell' at the blunt end of the egg.

* Embryo punctures the [[Exotics_-_Composition_of_the_Egg_- Anatomy & Physiology#Embryonic_Membranes|chorioallantoic]] and [[Exotics_-_Composition_of_the_Egg_- Anatomy & Physiology#Shell_membranes|internal shell membrane]].

* Embryo punctures the [[Egg Composition and Formation - Anatomy & Physiology#Embryonic_Membranes|chorioallantoic]] and [[Egg Composition and Formation - Anatomy & Physiology#Shell_membranes|internal shell membrane]].

** Able to begin pulmonary ventilation, rebreathing the 'air cell' gas.

** Able to begin pulmonary ventilation, rebreathing the 'air cell' gas.

** Transition from diffusive respiration through the [[Exotics_-_Composition_of_the_Egg_- Anatomy & Physiology#Embryonic_Membranes|chorioallantois]] to breathing through the [[Lungs_- Anatomy & Physiology|lungs]].

** Transition from diffusive respiration through the [[Egg Composition and Formation - Anatomy & Physiology#Embryonic_Membranes|chorioallantois]] to breathing through the [[Lungs_- Anatomy & Physiology|lungs]].

=== Heat Loss from the Egg ===

=== Heat Loss from the Egg ===

* Heat loss from the egg is prevented by a thin boundary layer of air adjacent to the [[Exotics_-_Composition_of_the_Egg_- Anatomy & Physiology#Shell|shell]].

* Heat loss from the egg is prevented by a thin boundary layer of air adjacent to the [[Egg Composition and Formation - Anatomy & Physiology#Shell|shell]].

* If the egg is in a nest, the nest will also provide resistance to heat loss.

* If the egg is in a nest, the nest will also provide resistance to heat loss.