Comparative study of embryonal development in 2 oviparous and 1 ovoviviparous species (Gallus gallus, Coturnix c. japonica and Liolaemus tenuis t.)

In a study of the development of two oviparous species (domestic chicken and Japanese quail) and one ovoviviparous species (a common lizard), the relationship to alterations in egg size and weight during incubation was examined. It was observed, as reported by others that the avian egg diminishes in size during incubation, but that the lizard egg increases in size and weight. This investigation examines these relationships and suggests that the increase in the size and weight of the lizard egg is a result of an increase of liquid content. The mechanism is discussed.