Variability in Development of Fresh-Laid Hen Eggs

Abstract

BIRDS represent a great class of animal life where the mode of development is discontinuous. There is, however, a definite and progressive development within the body of the mother from the one-celled zygote to the many-celled gastrula stage. This is followed by a resting period until incubation begins. The stage of gastrulation at the time the fertile egg is laid varies considerably with the time elapsing between fertilization and laying of the egg as Patterson (1909) pointed out. Stockard (1920) reports that Fundulus embryos in the gastrula stage show slight or no effects from exposure to refrigerator temperatures of 5, 7, and 9°C. When exposure was made in earlier stages mortality was high and later development very abnormal. Stockard suggests the possibility that abnormal development may take place in incubating hen’s eggs laid before the gastrula stage is reached. Such chicks may be so abnormal that they never emerge from . . .