Distribution of Mortality During the Period of Incubation

The factors which cause high mortality of chick embryos during the period of incubation are more or less obscure. Results obtained at the Massachusetts Agricultural College demonstrate that mortality is not evenly distributed throughout the 21 days of incubation.

For the past three seasons we have kept accurate records of the daily mortality from a portion of the eggs incubated at the College plant, and there has been a marked similarity in the death rate with certain periods of incubation.

The mortality by days was determined in the following manner. A number of eggs were placed under hens, and an egg with a normal embryo was broken every twenty-four hours from the first to the twenty-first day, and the embryos were mounted in glass jars. The dead germs taken from the incubators on the 7th, 14th, and 22nd days were broken, except the blood rings, and the dead embryos were …