Analysis of the Conditions Affecting the Existence and Growth of a Chick Embryo:II. Factors Causig Death in Chick Embryos in so-called Artificial Hatching, with Special Reference to Imperfect Inclusion of Yolk-sac within Embryonic Body Walls in this Metho

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To determine the relations between various states of the yolk-sac of a chick embryo in shell at the end of incubation and later develoment of the chick, the author observed exposed chick embryos taken apart in the air from their shell, shell-mem- brane, allantois, and amnion at the beginning of the pipping period.The following results were obtained from observations, 1) At the end of incubation the states of the yolk-sac were divided into three types: (a) completely enclosed, (b) just enclosed, and (c) still not enclosed within the body walls of the embryo.2) In the operation of "artificial hatchng" (optimum temperature 39°, relative humidity 60%), the death-coefficient of chick embryos was high, especially in the group with the yolk-sac imperfectly enclosed (types b and c).3) Only in 2 of 12 cases a small amount of residual yolk-sac outside the body was enclosed within the body walls after the operation.4) Chicks which underwent this operation showed a tendency to suffer from diarrhea and mostly died in 4 weeks.5) The average weight of surviving chicks was much lighter than the standard.dard.
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